livedo racemosa/allergic vasculitis??

My ten year old son was biten by an insect two months ago. The bite became swollen and red. The next day the lesion was not swollen anymore but he had multiple red raised spots on his arms and legs. My doctor told me not to be worried, cause the rash was probably an allergic reaction. A month later we went on vacation and I was still worried because the rash wasn't gone yet. I consulted a doctor again (during vacation) and he prescribed Prednisolone, because he thought it was an allergy also. Within a few days the red-blue raised spots disappeared and I was reliefed. After I stopped given him the Prednisolone the rash came back and this time the red blue raised spots were itching and on his arms, legs and buttock. He has no pain or other symptoms besides the rash I described. When he's sleeping or not moving a lot, the rash seems to fade away a bit. When he's moving a lot the rash tends to get worse. Last week (two months after the insect bite) I took him to a dermatologist and he called the rash LIVEDO RACEMOSA and performed a biopsy. I have an appointment scheduled to discuss the result of the biopsy in about two weeks. Could this be an allergic vasculitis, caused by the insect bite? How should his treatment be?  And what are the prognoses? I hope you can give me some clues about what he might have.
Thanks a lot!!

Greetings Sandra

[Sandra]

NOTE ON MY OWN POSTED QUESTION:
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Sorry, correction on my child's age, my son is eight years old and not ten years. Sorry about this.
Additional information about the medication my son got during the vacation: the doctor put him on Prednisolone for five days (20 mg dose per day) I forgot to ask the following question: if my son appears to have some sort of vasculitis, then why did the rash come back after I stopped given him the medication ?

Greetings, SANDRA