Poor little guy, thank goodness your husband has such a kind heart! Don't be too mad at him, his heart was in the right place.
I have never had a sick puppy, fortunately, so I am no help on figuring out what is going on. You have done everything I would do or suggest to do. Hopefully being back on meds will have him feeling better so you can get some food in him. That would be the most important thing at this point, in my opinion. I am so glad you have a vet with enough sense not to vaccinate this baby right now. Sending good thoughts he is soon the little terror we all know and love.