I don't know where to turn with this but I know there are a number of long term experienced dog owners here, and a lot of general knowledge.
TLDR at the end
Both my wife and I have been life long dog owners, and since we've been together we've often had two at a time, but never seen anything like this. When the last two died of old age we decided no more. We're getting on and we want the freedom of being able to travel, or just pick up and leave when we feel like it. That lasted about a year when we started looking, and found Nelson, a 4 year old hound that looks to possibly be a weimaraner cross. The retired couple said he just wasn't working out, they lived in the city and he needs a place to run. We have that. But we also noticed he came with a lot of different shampoos and whatnot. At first, and this was late fall, he was oily and stinky. We bathed him when we needed to and it was manageable. Then late summer next year he started scratching, and it got really bad. We took him to the vet and they gave us some shampoos. They did nothing. Then they gave us some pills. They did nothing. By this time he had no hair in a number of areas, including his face, was raw and bleeding in others, and losing weight rapidly. Then they recommended a cytopoint shot. This worked like magic and he was back to normal, not scratching, re-growing his hair and gaining his weight back. Everything was fine until late summer and it started to happen again. So we got the shot again. This time it lasted a month to sx weeks and he started scratching again. At this point he's scratching himself raw. He looks terrible and sleeps most of the time. We're trying to get him in for another shot, or at least some direction, but the vet is busy, short staffed, there are covid restrictions, and she appears to be not all the interested in the first place. We finally got an appointment for him next Tuesday, and I call every morning to see if there are any cancellations, but that's where we are.
It seems to me that there should be an answer here, but I don't know. Is he the problem, is it that difficult to figure out? Is the vet the problem, should I find another? I really don't know.
TLDR: My dog is scratching himself to death and I don't know what I can do about it.