Puppy (beagle) is throwing up and sick?

I have a 5 month old beagle who was rushed to the emergency vet about a month ago. The emergency vet took xrays and did a fecal sample on her for parvo. The parvo came back negative and the xrays showed inflamed intestines. I go home with flagyl and a week later shes still sleeping and diarrhea, the vomiting had not started then. So I made an appointment with my regular vet who said continue with the flagyl but I also told my vet when I lift my puppy up she grunts like it hurts her. The vet checked her out by pushing up and down her spine. She said she feels I am dealing with two issues (the inflamed intestines from me switching food too often) and also a possible bulging disk which is common in beagle breeds. She sent me home with rimadyl and as soon as I walked in the door, my puppy was acting better from the rymadly. Well we are almost 3 weeks into the rimadyl and she has no more left for the past 3 days. She doesnt want to move and when she does she can SOMETIMES be wobbly and/or her legs shake. WHen I get her to walk she does ok. Today she did not want to eat. I mixed in yogurt and she ate it fine but now is throwing up. She is drinking fluids and going to the bathroom. I called the vet earlier who said we will put her oon the rimadyl for one more week and if she doesnt get better she wants to see her again. Heres the problem: Im unemployed, there is nothing Ive found in my area that helps with cost (Buffalo, Ny) and Ive already spent $800 in vet bills. Is it possible that a dog can get sick from not being on her meds anymore? Im worried all these vets are giving me wrong diagnoses and I really cant keep paying for all of this.