I just finished amoxicillin for strep/sinus issued last week now i'm all congested again! thinking its allergy related, any otc could help?

Consider consult: Hard to know without more information. Allergy is possible, but so is inflammation from a partially treated infection. Sometimes a longer course of antibiotics is necessary for true bacterial sinus infection, particularly if there was initial improvement. Sometimes a short prednisone course is given to resolve inflammation and improve efficacy of the antibiotic. Consider a consult to discuss.