When i was a baby, i was allergic to erythromycin. is it possible that i am not allergic to it any more?

Very possible: Most intolerances are mislabeled as allergy. Ige reactions are rather rare. An accurate description of your reactivity would be crucial.

Yes: It is common for babies and young children to develop a rash with viral or bacterial infections; often, when a child with an infection gets treated with an antibiotic and develops a rash, the antibiotic is blamed. Discuss your situation with an allergist; it may be appropriate to do some skin testing or test dosing to determine your true status with regard to erythromycin.