My 42 Year Old Son Has Had Several Spells Of

My 42 year old son has had several spells of vasovagel syncope - all preceded by upset stomach feeling, feeling like you are going to throw up, He flies for business a great deal and this has happened several times after he has flown. After the upset stomach feeling he can feel that he is getting ready to faint and usually just goes ahead and drops to the floor so he will not hurt himself.