My heart goes out to you, your husband, and Rock Star. You definitely have been handling many difficult issues. I hope things will get better for all of you. I would recommend changing foods as recommended by others. I also give Buster Jarrow Petdopholis as he had issues due to antibiotics and they recommended Acidopholis for help with yeast.
Pet Dophilus or plain unflavored yogurt. I had a friend whose Yorkie also had yeast issues and she used
Best Supplements for Dogs or Cats | Nzymes.com and
Allergies in Dogs - Clearing the Confusion and Getting Real Help | NZYMES.COM
Best wishes to you all.