I have a friend who is a 15 year old male who had a stomach virus yesterday. he said he had some chest pains this morning and right now. is it dangero?

Gastritis: It is quite possible your friend is having some discomfort from acid in stomach/esophagus related to the stomach virus. This pain can extend up into the chest if he is having some reflux into the esophagus ( basically heartburn). Have him eat very small amounts of food frequently, drink plenty of water, try an antacid (tums, rolaids, etc), avoid caffeine and smoking. Relax- likely not serious.