1. Stop feeding him pure meat.
2. Start feeding him 2 cups of rice, plus boneless chicken breast (cooked).
3. Add 1 cup of Pedialyte with his feed.
4. Give him Immodium AD.
The dog needs FLUIDS and ELECTROLYTES if he's having so much diarrhea
I don't know what "run different kinds of wormers" means, exactly, as each one could have been given inadequately
At this point, I would suspect (as Loot says) coccidia, giardia, or some other microbe. There are 2 ways you can do this:
1. Use a combination of Fenbendazole (23 mg/lb/TWICE DAILY for 5 days + Pyrantel (16 mg/lb, also for 5 days). A synergistic effect between pyrantel and febantel has now been proven.
2. Metronidazole (12 mg/kg, TWICE DAILY for 5 days) + TMZ (50 mg/kg the first day and 25 mg/kg/day) for 2–3 wk thereafter
Given his condition, you might want to do all 4 of these, just to be sure.
If he's still symptomatic after this, then I am stumped.
Good luck,
Jack