My 5 year old has purple bruise-like spot on ankle. hard and raised on edges. pediatrician said use hydrocortisone which has had no affect. what now?

Bruise: It may take a week or two for the bruise to heal . Tincture of time is the treatment.

Many possibilities.: Hard to say without a photo, but it could actually be a bruise. I'm assuming it appeared recently, so it's not a birthmark. Other possibilities include an insect or spider bite, an allergy to something he/she came in contact with, or a focal infection. If Hydrocortisone had no effect, i would recommend an examination by a dermatologist.