White spot on back of sore throat. Infection or by-product of allergies?

I have had a sore throat for the past day or two. I have no tonsils so I guess I would have pharyngitis instead of tonsillitis. The throat appears red and agitated. I have slightly swollen lymph nodes on the left side (my left, and the worse side) and it hurts a little to swallow. Now a white spot has shown up as well. The odd thing is I feel just fine, no other symptoms whatsoever. I have been suffering from some nasty allergies lately so I was wondering if simple sinus drainage could be to blame for the symptoms or if I need to be hopping on the antibiotic train.