Red bumps everywhere in the back of my throat, could it be cancer?

Unlikely: You need to get a physician to examine your throat before you can be certain as to what these lesions are. Cancer in the throat, if present will cause a growth, or a tumor or an ulcer which does not heal for more than 4 weeks. It does not look like you have anything like that!. So you could watch it for a few weks to se if it resolves or go see your doctor if you are still concerned.