Feeding Issues...

Will just threw up absolutly everything that he could have ever ate in his lifetime. I am so upset, I have tried to feed him all day and then, right before bed he throws everything up. This is not good because he must keep everything down in order to gain weight and Dr. Barlow (GI doctor) asked when I talked to her today if he was vomitting, I said "no". But that has now changed!
Oh, I also talked to Dr. Rahman today (peditrician) and was telling him about what Dr. Barlow had said regarding the CT scan. He asked me if "Willy" (that is what he lovingly calls him, lol) had passed the barium that he swallowed during the upper GI last Thursday. I was like, what do you mean, would I know? He said that his poo would be white and chalky. I was like no, he has only gone once since last Thursday. Dr. Rahman said "Are you kidding me??" He said that he couldn't believe that he hasn't passed it yet. That sort of has me worried. But I guess since Dr. Rahman didn't say anything more about it, then I shouldn't be totally freaked out.
Will is now screaming his head off and Josh and I are not sure if we should feed him again, since the throwing up thing or not. AAAHHHH! This is so aggravating.