Ingrezza can cause slowed movements and drooling. Haldol can cause drooling as well.
Was he given the Ingrezza as a response to Haldol-induced Tardive Dyskenisia? Has he tried other antipsychotics before being put on Haldol?
Haldol is not usually prescribed in the western world, it’s a very old, “typical” antipsychotic. Newer, “atypical” antipsychotics have far fewer side effects.
Maybe ask the psychiatrist to put him on something newer!
As for the vomiting, he may need to change his diet to something less irritating to the stomach lining. Cutting out wheat is good for starters (raises zonulin, which breaks up tight junctions in the gut, causing autoimmune inflammation problems.) Also, would be good to stay low fat, low sugar.