Well loads of advice and your vet is involved so hopefully a happy result won't be too far off. I have a little rescued chi x Jack Russell. He was itchy scratchy and quite bald when I first got him. A gentle wash with a natural soap containing Neem Oil followed by bicarbonate of soda rinses worked for him. Sometimes it's also getting used to a new environment and different foods. Topo (my dog) was a constant paw sucker....it took months to train him out of it.....that's the thing with rescues....they need lots of time, patience, lateral thinking and buckets of love....the return...priceless.