I certainly agree about the second opinion. Something is wrong.
There are a lot of people on this board that have had this problem. Please hang on and keep checking back until they see it and respond.
I know canned pumpkin and yogurt with live bacteria is what is commonly used to help bind things back up. I know there was a joke at one time about how it looked like you were serving them with pumpkin pie with whipped cream on top (yogurt). I personally have not had to try this yet (thankfully) but those that have swear by it. They also say that the kitties like it and most of them don't have to be forced to eat it. Especially the yogurt. If you try the yogurt make sure it has live bacteria and it should say so on the carton. These are good bacteria that help destroy the bad bacteria in the intestines.
Your baby really sounds sick and I'm sorry to hear that. Please keep us posted and make sure you also watch for dehydration. If at all possible try to get a second opinion for the little guy.
Please keep watching the board because the experienced experts will eventually see this.
Good luck and hugs to your sweet baby. Prayers on the way that he gets well soon.