Help for skin irritations

I have a 12 yr old bichon frise - cocker spaniel cross. He has a number of lumps on his head, face, body and legs. Usually he ignores them, and the vet has advised us that these "warts" are likely benign and are best just left alone. However, when he gets back from the groomer, there are 1 or 2 that seem to really bother him. He scratches until the skin breaks, for a week or two after he gets home. He was just groomed about 5 days ago, and he's been scratching since then. At first it was just one on his face, so we put the big collar on so he can't reach it. But today he started scratching another one, on his shoulder, and he's now broken the skin, just a tiny bit.

Does anyone know of a good over-the-counter medication that can be used to reduce the irritation, or am I making another trip to the vet?

BTW, any ideas about what irritating these particular lumps? We have a really great groomer, and I know she's not accidentally nicking his lumps with a razor. She scissors his head, face and legs and uses an anti-allergy shampoo.

Thanks!

The shampoo might be aggravating the lesions even if it's hypoallergenic... What about baby shampoo? Maybe that would be gentler? I'm not sure, but if you are noticing that after a bath, the doggy is worse, it could definitely be linked. I would ask the vet about the open ones though. You don't want them getting infected. ;)