Hi, Glall stones are fairly common typically it hits women who are overweight, fertile, are forty (doctors learn it as the 4 f's female, fat, fertile and forty) so while you are younger and no longer heavy there is a good case for them having developed before surgery and since no one can prove it I think they would have to cover it. The further out you are the harder it is for your insurance to cover it. I am 11 months out and I get bouts of diarrhea about once a week I also get bouts of constipation it goes in almost a predictable cycle.