Allergies?

S had pink eye on Monday and I took her to the doctor on Tuesday. The doctor prescribed some erythromycin ointment for her eye and it started to look better right away. By Wednesday I had my doubts though. She was so purple under her eyes that I thought she had allergies instead. With spring coming and the crazy wind we've been having, I've had some symptoms and thought maybe that was her problem too. I've been giving her children's Benadryl but I can't say it is making a big difference. Could this be a cold? I'm still thinking allergies, but the poor child looks terrible and complains that her eyes hurt.