We've just finished two days of testing on Holland: blood work, CAT scan and poking in areas that don't deserve to be poked. Our pediatrician recommended having the CAT and seeing a gastroenterologist. He didn't seem to think the fluid in his abdomen was any big deal, but the CAT scan showed so much blockage in his colon. He said kids with tethered cord often have constipation problems. He's had this before. We cleaned him out with magnesium citrate and did Miralax and it seemed he was too "loose" so I stopped. I guess I won't be able to do that again.
Another possibility is celiac disease. I've done a gluten-free diet with him before, but it was so hard to keep. It's nearly impossible to avoid and the foods you can make with different kinds of flours don't taste that great. We stopped at the lab for blood work after his appointment and hope to get some results by Monday. He had to be poked twice because his vein collapsed while she had the needle in. His arms and legs are so cold (they get that 'mottled' look) and his skin is cold to the touch. We had to warm him up before she could get enough blood.