HELP MY RABBIT IS NOT EATING AND UNDER WAIT BY 5 LBS AND NOT EATING AND SHE IS REALY OLD?

My rabbit cookie is 9 yrs old and she just recently had and still has pneumonia and she got magets and so we gave her antibiotics and shee seemed to be getting beter but al of a sudden she stoped eating and started sneezing again THE BOTTEM LINE IS SHE IS WAY TO UNDER WAIT SHE SHOULD BE 5-7 LBS SHE IS 2 AND A HALF LBS!!!!! JUST TELL ME WHAT TO DO I LOVE HER WITH ALL MY HEART I HAVE HAD HER SINCE I WAS 2YRS OLD