My 30 y.o. son has had chronic vomiting since he was about 10. He has had every test the gi docs can think of, some more than once. They just can't find anything wrong, so they started him on antidepressants, he is sick again. This happens about once a month for 1 wk. The poor guy just can,t live this way. No obvious trigger can we come up with. Any ideas?