And these mini drug store clinics, I think do no more that treat, very minor issues, and tell you to go to your Primary Care doc if you need lab work.
And a simple multi, which only contain trace vits/mins with a acid reflux med will only mask the issues.
Individual vits/mins, acidopholis can and do help folks.
BUT before any blood work can be done, a person has to be off all them for 2 weeks. I know this because I take them, and had to be off 2 weeks just to get a platelet count done.
That was my first thought. Gluten allergy.