COuld be neropathetic gastroparesis, but it could be the allergies as well. I've had that issue. Is he on sensipar for elevated PTH?
Its so difficult to say ..there are so many reasons , i have had stages like this. It could be a build up of toxins or a medication or an ulcer. I was throwing up all the time , couldnt keep anything down , but no real reason why not , then it just seemed to go as quickly as it came. Trouble is we all immediately think kidneys when it could actually be a stomach bug. I hope you get it sorted quickly..more tests?
Is he on pd? If so make sure they do an ct scan of his stomach. I had this problem and it turned out there was a blockage in my intestines. I had to have surgury. I guess the number one thing is keep complaining till Richie gets some relief.