Strep throat (although tonsils look clear). took 1 of 3 azithromycin 500mg last night. today tonsils look visibly worse. wondering if: a) the antibiotic's not working b) working just need to give more time c) i'm contagious (told i wasn't after 24hr)?

Hard to guess: If the throat swab was positive for strep throat, and/or the doctor did a thorough evaluation of the patient's history, symptoms, and examination, then the diagnosis is likely correct. It usually takes 2 days for symptoms to decrease. It's safest to assume contagiousness and not unintentionally transmit the illness to other people... until maybe 7 days after the start of treatment.