Feeling vomit. Much diet and complaints!

Hi, My dad for past few days has been facing some problems with eating food. He complains of vomit, however it just feels like vomit and there is only spit coming out with dry cough. He is not taking much diet and complaints regarding the same of light chest pain and vomit. He had one of his tooth removed recently and took medication for the same. We have tried giving liquid diets and stuff. He is hungry but can't eat anything. His oxygen level is 95-98 and BP is normal. And no other current helath issue sort. Poosibly it could be a heatstroke or something. As he also complains about light chest and stomach pain.  Need some viable solution to be resolved at home. I believe it is not covid 19 as my mother at home is sugar patient and she would have been infected as well. My father's bp today latest was 133 / 92. So it's kind of normal and fever temp was 96.1. We have given him vitamin c and zinc tablet to boost immunity. Please suggest home remedy of diet and food.