Enlarged tonsil since mid jan. two courses of antibiotics. terrible pain behind right tonsil with a grey/white spot?

Tonsillolith: Grey/white spot behind or on right tonsil with pain sounds like a tonsillolith. A tonsillolith (or tonsil stone) is a collection of trapped debris that lodges in a crevice in the tonsil. These can cause a foreign body sensation in the back of the throat and sometimes pain. Please see an primary care physician or an Ear, nose and throat physician for removal and to evaluate for other causes.