Why don't you just request that they do x-rays and bloodwork? If they don't take you seriously, call a vet who will do the tests that you have requested. It sounds like it's possible that he may have an obstruction or he may have swallowed something that is harming his insides. I wouldn't take any chances. Or it could be something unrelated. Good luck!!     
				__________________  Miko   's his Mommy     |