Whatever this natural treatment you have been doing isn't working, so please stop making both of you sick. Dogs don't usually show how they feel until they are really bad. Bless Nina's heart but she is 14 years old, that is very very long life for a large dog. I know you are trying your best but I don't think it's working, look for a plan B. Ask yourself, what is best for Nina and what is best for you?
Please take care.
~Hope