Soft coated wheaten skin issues Discussions

So I have a 2 year and one month male wheaten. He is a great dog. We are in love with him. He recently developed bumps on his skin. It resembles heat trash. We gave him a short haircut. It seems to not have helped. He had been licking bumps in the groin area that seem to have become infected. The vet gave him an antibiotic. This did not rid him of the bumps. I returned to the vet after 4 days after the medication finished and the irritation was worse. She then suggested an allergy antihistamine injection. This didn’t seem to do much. I brought him to the vet to be groomed . They cut his hair short and used medicated shampoo that I then purchased. I’ve been bathing him 3 times per week with that shampoo and it seems to be the same. Any suggestions? He never had anything like this before.