1. How long has he had symptoms?
2. Will he eat treats?--meat, whatever is a treat for him?
3. Is he drinking, peeing, and pooping?
4. How do his gums look? (pale, or normal, if you can't tell, compare to another dog)?
5. Is his belly soft? Can you feel any masses? Can you hear bowel sounds? (put your ear to his belly, you should hear an occaissional tinkle, none or lots is not normal).
6. Is his breathing normal?

He really does need labs and possibly X-rays done--the symptoms you describe could be just about anything, including something pretty benign like an infection he picked up from eating trash on the ground to something serious.

If you absolutely cannot get him in for tests, I'd put him on some antibiotics for 10 days or so (like flagyl). Usually won't hurt, might or might not help.

In the meanwhile, make sure he gets enough fluid.

Jakes mom