vomiting post Nissen

Had surgery 15 months ago....only one episode of dry heaving which scared me....I was reading on other posts about the Vagas nerve and that it could be damaged during surgery....was also surprised to find that problems arise when involving a hiatal hernia (which I did, now fixed) and migraines in the left eye were an indicator of Vagas nerve damage....I've suffered horrendous migraines from age 13 (onset of menses) which have seemed to diminish with menopause. No doctor I've ever seen has made a connection and just treated me for the migraines with Fiorinal (an old medication but works for me)....also experienced vertigo for which I was given a CAT scan, no signs of anything abnormal came of it....just wondering how common/uncommon this syndrome is and if I really do have nerve damage.....how can it be found out? I've had several endoscopies but none post Nissen.....thanks for any and all insights:)