Thank you for your query at DoctorSpring.com
I can understand your situation. Based on the description and the clinical photographs, rash appears to be allergic. There is clear erythema and wheals are also visible.
Allergy could be to multiple things- It could be to drugs, the underlying infectious agent or something unrelated. Stopping Azithromycin is definitely the first step. You could consider using an antihistaminic such as chlorpheniramine, fexofenadine, levocetirizine, etc if the rash increases or persists. You need to give your baby plenty of fluids and ensure only symptomatic therapy with paracetamol for fever control. If the rash increases despite discontinuing the drug, it could be an allergy to the underlying infectious agent or to something else. In that case, you may have to visit the nearest hospital to get a few tests done. You may also need to take your baby to the nearest pediatric emergency if the rash increases rapidly or any new symptoms suggestive of respiratory or hemodynamic compromise appear.
Hope this was helpful,
Please feel free to discuss further
Regards
Dr. Saptharishi L G