I Had A Small Pea Size Cyst That My Dermatologist

I had a small pea size cyst that my dermatologist looked at about 6 months ago and said it was nothing to worry about. Now it has gotten huge, is red, inflamed and hard and hurts. I am on penicillin from my GP - but what comes next. I am going back to the dermatologist tomorrow who visits our town once month - can he drain or take it off if it is infected like this?