My Son (19) Who Is Home From College Is Throwing

My son (19) who is home from college is throwing up, has pain in his stomach, and can't sleep. What should I do for him? He is very uncomfortable. My father-in-law who is visiting was throwing up yesterday, and 24 hours later he is feeling better. I'm just not sure how to comfort my son. His stomach pain seems worse than my father-in-law's.