My Son Has Had Several Issues Of Sudden Nausea, Vomiting

My son has had several issues of sudden nausea, vomiting and chills. It lasts for several hours. It seems to have started after going on an anxiety medication for high blood pressure. ( I don't know the name of the medication). It seems to occur (usually) after eating spicy foods or peppers. His doctor just says don't eat spicy food. My husband and I have seen how quickly he becomes ill and it is very concerning to us.