Sudden hot/warm sensation on right side of face. i looked in the mirror and that side of my face is red exactly where the warm part is?? only 1 side.

Inflammation: Redness and warmth of a body warmth is the classic sign of an inflammatory process but exactly which one and how best to treat is what only a doctor who examines you can determine. Sometimes it may take additional testing with blood, urine, and other tests. Sometimes just by inspection. You should seek out a physician who can take a look at your face. Good luck.