I have a swollen lump in the back of my throat on the right side. there's no pain or redness, but it has a white spot on it. what could this be?

Maybe a big tonsil: Tonsils are part of the immune system. When enlarged, they look like an oval lump on the left and right sides of the back of the throat, behind the tongue. Big tonsils can have little whitish lumps of material stuck in them (theses would be called cryptic tonsils, with the crypts being the holes containing "crypt debris" or "tonsil stones"). A primary care doctor can evaluate and treat as needed.

Tonsil "stone": The most common reason is tonsil debris, otherwise called a tonsillolith. This usually is just irritating and for some causes bad breath from bacteria. If it does not disappear within a week or two, especially if you gargle, have your doctor or ENT check it , to make sure it is not a lesion that needs a biopsy.

Possibly a tonsil: It might be your tonsil with a small chunk of debris within it. There are various names for the material including tonsil stones and my favorite "tonsil cheese." your doctor should be able to check this for you. Tonsil cheese is common and not dangerous although it can be annoying and give you bad breath.

Tonsil stone: Agree with all of the physicians who have answered. Aggressive gargling or the use of a waterpik may help keep your cryptic tonsils (tonsils that have deep pockets that trap debris) clear.