Dog not eating or defecating

Our 6 yr old mini poodle-jack russell mix hasn't been eating for the past week. Before the visit to the vet we would give him half a pill of baby aspirin twice a day, we then hand fed him some chopped up bacon and he loved that. He would walk around a little bit but then would get tired and lay back down for the rest of the day. We got very worried so we took him to the vet. They had done numerous tests such as a ultra sound, blood test, parvo& heart worm tests, along with a urine test and everything came back negative. We have spent more than 1200 dollars...the vet has given him 3 pills aciphex,Famotidine,mirtazapine and metocloparmide. There's no improvement but appears to be more weaker.   What should we do?

[ginger899]

This is a lot of meds for a little dog...What was the initial diagnosis which caused him to need all these medications? Did he have irritation of the stomach lining?
AcipHex and Famotidine appear to be different meds that do the same job, blocking over-production of stomach acid. Mirtazipine is an anti depressant, anti-nausea drug? And Metaclopramide helps 'speed up' the passage of food through the stomach. What stomach problem was first diagnosed? What did you have to give him the aspirin for, before the visit to the vet (when the other meds were prescribed)?
If he hasn't been eating for a week, he will be feeling weak. Is he drinking enough? A glucose/water mix might help support him, but this sounds like he needs to go and get checked by a different vet. If all these anti-nausea, anti-stomach acid drugs are resulting in this outcome, (ie not eating) this needs to be sorted out very soon.