Anxiety, Fear of Death, over thinking ,

My dad is suffering from problem of Anxiety for last 3 years . He have been a very responsible and dedicated family man . He is very intelligent and hard working. In 2015 he lost his Father and then in 2016 his younger brother died . These years were very difficult for us even we all were at the verge to lose our mental stability due to some drastic family crisis. We were emotionally as well as financially unstable due to his younger brother. It was only him who was handling all the problems single handedly. There was no one to  support him. Now whenever his gastriac issue arises it makes him lose hope of living. He starts thinking about everything around like career and marriages of his kids and what not . He is under various medication for last 3 years. Most of his medical reports are normal but he still consider himself a heart patient . He anticipates heart attack very often. He always asks people if he is looking weak. Superstition is part of his life now. Plz help