Bumps on skin

What dog feed are you feeding? Try a couple months of Diamond Naturals Chicken and Rice. It has no corn in it.

Bath him with a medicated dog shampoo only once. Do not use dish soap and do not bath him often. Bathing often strips the natural oils .

Treat him with something that will kill all fleas,ticks, mites, etc. Tractor Supply has a great product called Prolate/Lintox.

Treat his kennel,dog house, yard, etc. with a good insecticide. I use Cutters Back Yard Bug Control. Soak everything down with it.

Find you a tube of Nu-Stock. Squeeze all the Nu-Stock into a big squirt bottle. Add to it a big bottle of baby oil. Shake it up good. Spray all them bad spots with it daily.

I had a young dog with bad skin problems. Vet could not figure it out. I did everything mentioned above and in a month he had the most
silkiest looking coat of hair you ever seen on a cur dog. Never did figure out what it was but after doing the above on the advise of a friend, It cleared up. Sometimes it's just a week immune system. Might also give him something for that.