I noticed a small lump in the back of my throat right behind my tonsil that causes pain when i swallow. the limp is a light orange red color. cancer?

Very unlikely: Go see your doctor for an exam. Tonsil cancers are generally painless, often difficult to see by eye, and begin appearing usually in the 30s in non-smokers.

Most likely benign: Although cancer is possible, it would be very rare in your age group. This is most likely inflammation from a recent upper respiratory infection or allergy. Nevertheless, if this does not resolve in a few days, ask your doctor to look at it.