Could you please help me...

Hi my fiance has been going on 2 weeks of having abdominal pain and loose stools. Going to the bathroom every 5-10 mins. and everytime he eats chicken noodle soup he have to go to the bathroom not even 3 mins. later. He can't hold down his food while going to the bathroom afterwards. I am very worried. This stomach pain he's having occurs just about every year and about the same time of the year. Also he at bad nacho cheese the other week and not sure if he got food poision from the cheese since it is now ongoing for 2 weeks of going to the bathroom and stomach pains. He is also strainning and hurting when he goes to the bathroom.