Dog diarrhea that won't go away.?

My 6 month old English Mastiff has had several bouts of diarrhea since the day we got him. At first it was from worms and the vet helped us clear him of that. Then it was because he ate a rawhide chew stick whole. The vet said it would p and not to worry. The next visit to the vet, he told me that puppies, especially bigger ones like mine are chewers and he'd probably continue to get diarrhea throughout his life. Well, this last bout has lasted almost a month. I see a few times that he has a solid bm, but mostly it's liquid or mush. My other dog is pregnant, I am pregnant with twins and have absolutely no income. So please don't tell me I need to rush him to the vet, because he never seems concerned anyway. This last time he ate a barbie along with cardboard, some rocks, and god know what else. He ped a foot the other day. Is there anything I can give him that can help him to p anything else that might be in his stomach. he acts perfectly healthy, eats full meals and drinks plenty of water. Help if you can. Thanks