75 yr old woman has hernia operation, suffering from nightly post surgical itching, have seen derm, allergist, etc. no explanation, any ideas?

Some ideas....: 1. Check w surgeon to make absolutely sure no foreign object is in wound or inside that is causing allergy sx. 2. Dry skin--drink 60 ounces of clear fluid daily; use skin moisturizer after bathing or twice daily in all itchy areas. 3. Taking any new otc or rx meds at all? If yes, stop them; any new cream, soap, detergent, wound cover material? Perhaps spring allergy, nothing to do w surgery.