did she have antibiotics after surgery? i cant stress enough and i know that i sound like a broken record but the immune system is the core to a dogs overall health,if she has had antibiotics i would give her acidophilus which will help replace the good bacteria which is often destroyed by antibiotics,also as she has just been spayed it could be her hormones dropping ,when hormones go crazy it can cause hair loss/allergy symptoms,a good quality food and immune boosters will help,omega 3 or flaxseed is a great omega source and grass grown beef/organs are very rich in omega,im fighting allergy type symptoms which according to my vet and after doing a lot of research may have been caused by her first season,so i am boosting her imune system ,i also give her a product called canine puriphy which is milk thistle and other herbs which builds up liver function,i also put a tshirt on her to prevent secondary infection due to scratching also i put calamine lotion on her,but only on her belly where she cannot lick as it can make a dog ill if its ingested,i hope you can find whats ailing your dog ,its very frustrating and time consuming ,and a lot of trial and error,im trying to get my girl sorted by using all natural products ,as drugs and steroids only weaken imune systems so really though it cures the initial illness/allergy the issues will return,i do give antihistamines twice daily ,i give them at breakfast and bedtime as i find she itches more after sleep,as they do give instant relief ,ive tried to research hostilic antihistamine but cannot find advise!!,karen