Why is my Ipod acting really weird?

So, I was having problems with my Ipod. I think it was because I charged it into my "MyTouch" cell phone charger in the summer (by taking out the phone usb and putting in the Ipod usb into the charger that goes in the outlet). When I played a song and would move the Ipod to put in my pocket, it would stop, then skip to the next song, and then stop again. It got so weird that I would try to go back to the original song after it skipped and then it wouldn't let me. I would turn off my ipod and it would turn back on, and even when putting the lock switch on. I tried to listen to it on the treadmill but it did all of these things like when I tried to use it at the gym. So I plugged it into my Imac, opened Itunes, and clicked "Restore". I did this yesterday and it was working perfectly fine but when I went to go on the treadmill today it did the same weird stuff. Does anybody have any suggestions? I really don't want to buy another Ipod. It's the older long thin Ipod Nano. Thanks.