Overheating Galaxy S3
So I've had my Galaxy S3 since April of 2013. I don't know if this is an important thing to note, but I've had problems with the battery in the past (it only holds a charge for about 4 hours if I'm using it minimally, at the most 6.) About a week ago I had it charging while I was asleep (so around 6 hours,) and when I woke up the phone was literally too hot to touch without burning the tip of my finger. There was also a notice on my phone saying, "phone stopped charging due to overheating," or something along those lines.
Since then, my phone has shut off (with a midway/full charge) randomly, after the screen flashing off and on for a few seconds, due to what I'm sure is also overheating (never as hot as the first time, but still hot enough to be uncomfortable to hold,) about 3 times now. It won't turn back on until it's completely cooled again, and needs to be charged (much longer than it needs to be charged normally.)
Is there a way to fix this, or am I just gonna have to bring my phone into AT&T?
Thank you very much for any help you can give me! With all the news I've been hearing about S3's catching fire, I can't help but be a little worried!