Titus Has Mosquito Looking Bumps On Back Towards His Hind

titus has mosquito looking bumps on back towards his hind legs and including his legs. he is continuously scratching himself with no relief. numerous trips to the vet prescribing strong antibiotic (2x ) steriods (2x) changing of his food several times, shots to relieve the itch and baths. nothing has worked. vet now wants him to see a dermatologist. please help my dog