Hello
There are two different symptoms.
Pain in the stomach and
nausea are related to each other , as these symptoms are for several days and may be due to hyper acidity or
gastritis or
hiatus hernia ( one and same thing ) , diagnosis can be confirmed by upper G I
endoscopy . When such symptoms present , please avoid spicy , greasy , fried foods , don't eat pizza , burger , sweets .
Try raising the head of the bed of your husband about 4 inches with blocks. It might also help to avoid eating or drinking for 2-3 hours before he lie down. Also take some
antacid but if there is sever pain and nausea , he may need drugs like pantaprazole -d once or twice in day for 10-15 days.
He is also having phlegm with cough , if he is a smoker , this is common .
If he is not smoker then get in X ray chest because his phlegm was brown color .
In my opinion consult a physician because your husband is also feeling weakness beside other symptoms.
Good luck.