Sorry to hear you're having this problem. At this point, I would give it a little more time on the anti-depressents, because they do take some time to work- at least 2 weeks, and maybe as much as 2 months. Also, I am sure your vet checked for this, but just in case he/she didn't, what about an internal perisite? (spellcheck on that). That is fairly common to pick up in the water or from another dog. Also, I had a dog years ago that had some kind of 'intestinal disturbance' the vet called it. It was a long time ago, so I don't remember what it was caused from (I think it was bacterial or maybe viral). I had to put him on a diet of ONLY hamburger and rice for quite some time. I don't remember if there were meds involved. It cleared-up after a very strict diet and NO treats whatsoever. Good luck to you, and let us know what happens.