Is it deeper, like in the eardrum, or more on the outer cartilage? If it's deeper it's probably sinus pressure. If you don't think that's it, maybe an ear infection.

I can tell you though, when I was a kid I got an ear infection that just couldn't get better. Finally I decided to lie on a heating pad, and I accidentially fell asleep. When I woke up 2 hours later my ear was hot as hell of course, but the infection was cured.