I am sooo sorry your Yorkie is so sick! It is very scary! We love our dogs so much and when they are ill it hurts Very much to see them unwell and not feeling good . I am glad you took him to the vet and he is getting treated. He has other medical issues too , I can imangine that this is extra hard on you .
Suzi has been pretty sick once and I broke down and cried, right in front of the vet. She was not as sick as yours , however had the exact same symtoms. I never did find out exactly what caused it. She was treated with anti biotics and something to settle her tummy with.
YT'ers understand how you feel! It is very heartbreaking, and a helpless feeling when our babies are ill! Those eyes looking at you, pleading to help them feel better! I have seen that look and it nearly killed me! you are not alone , and i do hope your boy feels better with the medication.