What would cause this ?

my dad has been sick for a week . hes had throwing up diarraha that has been black in color . he cant eat because it causes bad stomach pain and all the above . hes bloated and has gas as well. he has been really stressed for 6 months lost his job has to have back surgery and my mom wants a divorce! hes trying to pay for everything by himself and is just stressing out . what could this be he has lost 40 lbs in 6 months