I just posted a few hours ago, but I think I may have figured out the cause of my problem: water in my sinuses. I got quite a bit of water up my nose yesterday due to jumping into water feet first from considerable heights, and I remember feeling that burning sensation in my sinuses right after jumping. Then when I tried to eat later in the day, the pain in the roof of my mouth was unbearable.
Today, I looked at the roof of my mouth in the mirror and it is noticeably bruised and discolored. My theory is that all the water shooting up my nose and into my sinuses may have actually bruised the area surrounding the sinus. That would explain why cold liquids make it feel better, right?
Anyway, just a theory. Hope this may help someone!