Well, MDs just send you away when stuff doesn't go away or they think it's serious; I think Watson can easily be instructed to do the same. If it belongs in the category 'probably needs expert' he should pass his conclusions about what it is and so on to a human expert. Similarly with the cough he subscribed medicine for and after 1 week it's not gone yet; expert. This is what human MDs do as well and I had MDs actually tell me to 'be a man, suck it up' so not sure if Watson could do worse.

Fed with enough medical knowledge, Watson would be the expert.