What Causes Tonsillitis With Swelling And Allergy?

Hi... good day, I have tonsillitis about a month already. I've been 3doctors already. And they both said its tonsillitis. They both gave me dosage for it. But im little confused why until now my right side of tonsil still big. and the doctor said.. i have a allergy too. Plz. Can u help me what exactly i have...