Taking care of my sick dog

I have a 12 1/2 year old Lab who is an amputee because of cancer. (She had her leg amputated 2 years ago)She started throwing up over the weekend. Test confirmed she has a recurring bladder infection. The Vet put her on an antibiotic, which upset her stomach.Thursday she was not feeling well at all. I needed to get food in her system so she could take her medications. She would not eat the small portions I put in her bowl, which mean she is really sick because she never refused food!In the evening, I sat with her off and on and fed her by hand. She took little bits here and there.The next morning she was bright and chipper and begging to eat.