Im no doctor, but I would be quite careful if I was in SWIY's position.. IF I would try something, would definitely be VERY low doses and increase slowly. Is there any doctor aware of SWIY's condition? Maybe SWIY can ask, for example, if taking moclobemide (a MAOI-based antidepressant) would be dangerous in his case...
Also, ayahuasca has several somatic effects, and SWIY with his condition, even if everything is going fine, but because of these bodily effects, nausea and so on, SWIY can start feeling like he is having some serious issues, will get scared and can turn the trip into a very negative experience..
IF I would try something in SWIY's case, it would probably be smoked dmt, in VERY low doses (start at something ridiculous like 1 mg) and get an idea, increasing slowly and gradually if all goes well..
but its definitely recommended one checks with a trustable doctor (not one which has the 'drugs are bad' sort of opinion). Maybe email Rick Strassman, Charles Grob or other doctors in 'our' field.. If their mailbox is not overflooded and they miss your email, they will probably give you a better answer than most of us could.
good luck and please, be careful!