You may want to go see your dentist or regular care physician to find out what it is. Off the top of my head, I would guess it might be herpangina or a severe case of cold sores, both of which are viral infections.
Sorry. I am unable to diagnose over the internet. I can only provide advice and its hard to really offer any type of home cure if I don't know what it is.
I can't go to the doctor.. I don't have health insurance. So I kinda need to figure out an at home cure or something.