Can't put in contacts without eyes burning?

Last night I slept with my contacts in (I know you're not supposed to but I do it all the time and have never had a problem, I always put in eye drops in the morning and don't try to take them out upon waking up. The contacts I had in were probably about 3 weeks old, and this afternoon the left one started burning out of nowhere. I took it out and found that the edges were folding in (making it almost square shaped), but when I soaked it in solution it went back to normal. I tried to wait a while and put it back in but it still burned, so I assumed they were old and maybe splitting and took them both out. I tried about 3 hours later to put new ones in and it's still burning, so now I'm wearing glasses. What should I do?