I get a stray about 20 months ago. She is a tremendous dog. We have completed all that needs to be done for a brand new dog, received her the shots, received her microchiped, had her mounted, purchase her good pet meals (nutro max). Instantly they stated she had a problem with Mites. He gave me a shampoo to use and things began wanting better. After her surgical procedure, they got slightly worse (4 or 5 extra spots) and we observed a small lump where her incision was. We took her in immediately and had been informed that she was having a reaction to the dissolving stitches and we had been despatched home. We also put her on Vectra 3-D (flea and tick medication). In the present day I went to the vet again. Yesterday that spot looked prefer it had a dime sized blood blister. Right now it had broken open. After I took her in he stated she had been licking the spot and had irritated it. she was put on antibiotics and we had been also instructed her immune system have to be the underlying drawback as a result of she isn’t able to get rid of the mites or quickly heal from the surgery (7 weeks in the past). She now has a cone on her head (which she will have to put on till it heals, maybe one other month or extra) I asked what I could do to help her immune system and he mentioned I could not do much. I feel like I should have the ability to do something to help her, however I am not aware of canines immune systems. Please help I need her to be healthy.

I found a stray dog (mix of llasa apso/poodle/terrier!!!) in a rubbish bin,  almost 1,5 years ago. He was in a terrible shape, no hair, and stank to high heaven. The first vet I took him to, diagnosed mange (demodex) so I did the treatment (dips) for 12 weeks, and then he tested negative.
But 2 months ago I tried a different vet, as I wasn’t so happy with the other one. He found that the dog has Leishmaniasis, so I am treating with Allopurinol.
He also has mange again, which apparently is because his immune system is not working properly.
He also has infected paws, the antibiotics do not seem to be improving the condition much.
I don’t think he was weaned by his mum, which is why he has all these problems, so my question is:
Does anyone have a similar experience, and can you suggest something to boost his immune system? He is a lovely little dog, and is very happy, but I would like to find a cure for him.