IPhone 4s not charging correctly and shutting off intermittently by itslef?

I have had my iPhone 4s for about two years. It has worked well with out problems. Just the other day it began giving me problems charging such as I plug it in and instead of the lighting bolt where the battery is to indicate charging it will sometimes give the plug icon over the battery which means it is fully charged even when the battery is not even close to full and doesn't charge. Also, the battery percentage has been fluctuating oddly such as it will be 94% and dropped to 60% or go all the way to 1% and jump back to 90% without being charged.

Sometimes it charges without much problem and then even more recently the phone has been freezing up while I'm using it and then powering off and restarting all on its own. It has now happened at least five times today.

I tried doing a hard restart. Problem still occurs. I have also used different chargers and connected to the computer and wall outlet.

Has had trouble syncing because it has shut off during the sync.

This is very annoying any help or tips are welcomed!

Thanks!

Added (1). I know that what do you suggest I do?

Probably not working