My iPod Touch (5th gen) is deleting a GREAT amount of music upon syncing with iTunes. HELP

Question

It all started on Saturday (February 22), as per usual, I connected my Ipod touch to my pc and I have it connected so that it syncs automatically. I was going to do my daily workout and I had a song playing on repeat. It could be possible that I started playing the song while it was syncing, but I'm not too sure. When the song had repeated two or three times, my iPod stopped playing music. When I looked at my iPod, it had the "play" symbol, but the song was not playing at all. I looked at my iTunes and it showed that my song was missing even though it was clearly playing moments ago. This has happened to me a couple of times before and all I did to fix it back when it had happened was just to disconnect and reconnect my iPod.  Then the "!" marks would disappear, but that didn't happen this time around. I should also mention that I have the 64gb iPod Touch with only 6gb free (at the time when the iPod failed) and I had around 6,000 songs. Maybe 5,000 (I don't remember). So when I reconnected my iPod, It showed that there was around 20gb free and there was around 4,000 songs in my iPod (so it seemed that I lost around 2,000 songs). At this point I started to panic and I did not know what to do. When I tried to play my music on my iPod, it just kept skipping songs until it found one that it can play. But when I skipped more songs and tried to go back to the song that was able to find to play, that song was just skipped. I should also mention that I DO NOT keep a backup of any of my music. I then decided to use a program that I have that can export my music from my ipod to my pc. When it finished exporting, I noticed that It only saved around 3,000 songs (so I lost half of my music). Then I looked at my iTunes, it said that there was 4.000 songs in my iPod. I looked through the music that my iTunes detected on my iPod and found songs there that were not shown to be exported, but they were unplayable. When I looked through my ipod for those songs, they were not there. I disconnected my iPod, reconnected it, but the songs were still missing. I then decided to sync it (up until this point, I had Auto-sync disabled) and the 20gb of free space turned into 50gb of free space. I had no clue what was going on and was afraid that I had to restore it. I looked for solutions online and could not find anything. I restarted my iPod in hopes that something would happen, but all that happened was the 50gb of free space turned back to 20gb of free space. Nothing was working so I had no choice but to restore it.
Also, I had a manga app and the chapters I had downloaded there were also deleted (meaning that music was not the only thing that was deleted). And in case you were wondering, both my iTunes and iPod were up-to-date at the time.
It is now Thursday (February 27, midnight, with around 4,000 songs) and I was adding some lyrics to a specific song. When I tried to play this song on itunes, it gave me the "!" mark. Then I noticed that my iTunes was syncing with my iPod, but it was stuck at "Step 4" of synchronization. Growing impatient, I decided to take my chances and disconnected my iPod. I searched my iPod for the song that was missing and when I found it, I was able to play it with no problems. I restarted my iPod and reconnected it again and it started syncing (even though I have auto-sync disabled) and was stuck at "Step 4" again. I disconnected it, restarted my iPod again, and searched for some answers online. I then found out that there was an update for iTunes (11.1.5). When it was finished, I reconnected my iPod and the synchronization problem was fixed, but then it showed me that my iPod had 51.47gb of free space and more than half of my music was gone. My iTunes CURRENTLY shows that I have 2,544 songs in my iPod, but when I shuffled all my songs in my iPod,  it showed that I had only 327 songs. I learned my lesson from last Saturday and now have all my songs saved so getting back my music (right now) is no problem. However, I'll probably have to restore my iPod just to be safe.
Any ideas of what might be causing this? I do not want to keep repeating this process. I'm a big music person and losing thousands upon thousands of songs pains me greatly. I don't know if this is relevant or not, but I like to listen to my iPod when I sleep; so basically my iPod is playing for 6-8 hours every day (while charging). I've been doing this for 4+ years and it never really caused me any problems. Also, I keep my music very organized with labels and tags in almost every song along with a lot of playlists. Before this whole incident happened, I had over 200 playlists. I don't know if that might have.. "overloaded" my iPod? but yeah. Thank you for your time. Please Reply.
-Windows User-

Answer 1

I would either say that the iOS is correpted due to a software glitch or y have have a hardware problem like bad memory locations that are corrupting the iOS.
- Restore from backup via iTunes. This will install a fresh copy of the iOS. See:                                                
iOS: How to back up                                                                                     
- Restore to factory settings/new iOS device.   This will elimate corruptin in the backup causing the problem.          
If still problem, make an appointment at the Genius Bar of an Apple store since it appears you have a hardware problem.
  Apple Retail Store - Genius Bar