Hi, welcome to the forum, your history is suggestive of that you are having drug allergy to azithromycin. Some patients have reported to have itching (in about 10%) and development of rash. If drug allergy is suspected you need to report your doctor immediately. Further exposure to drug may generate more IgE levels and can worsen the condition. Itching is a milder form of allergic manifestation. Even drug allergy can lead to hives including life threatening reactions.
The itching can be treated by use of systemic anti histamine against prescription. You may need to avoid future use of the offending drug such as carrying a card. I suggest you to consult physician. Take care and regards.
You should discus this with your dr ASAP. It could be an allergic reaction or it could be something else. Let us know how you are doing.