Hi I Have A Sour Taste A Lot In My

hi I have a sour taste a lot in my mouth sometimes cramping with it and I am just wondering what could be possibly causing it my doctor just put me on a new stomach med to see if that helps hes not sure what it could be he said if he cant figure it out he may have to send me for an endoscopy I have already had my gall bladder out 6 months ago