Stomach Problems (Bad)

I'm 65 yrs old and have been going thru stomach problems most of my life. I've had every test given to me by many doctors and they say either it's acid reflux, irritable bowl etc. But I under stand from another  Dr's opinion that of all the test that I 've been thru for my stomach, their is another test which I have not been given??
I'm not sure of the pronuciation but the closest I  can remember was a test called Celiact Test? I've been on milk
and Mylanta for weeks at a time and that plays havoc with my bowels but it does give me relief ! Can you help with
the right spelling of this test??

[skylark17]

Celiac