I am not sure on the itchy red bumps unless it is a form of mites. As long as you are able to pick up, handle or move your cockatiel under normal circumstances I really don't think a trip to the vet would stress him enough to kill him. If your bird has never been handled are you able to take him cage and all to the vet? As long as you go to a true avian vet he should be experienced enough with birds to know the correct way to get him out of the cage without causing undue stress. Also if you know a good avian vet you could call and ask there opinion on this but I would say if there is any way possible try to get him to a vet.