how to determine if is/isn't gerd?

Here are the symptoms I more or less have, and am asking whether someone knows if it may not solely be Gerd (had Ba swallow and said it was possible, not quite conclusive thoug) and could need further MD looking at?

1) cramp/burn around the right lower rib area and bit under sometimes, aside from around area of stomach. other abdominal is about the pelvis (varies, not sure if internal or bone) and on the lower right side of back
2) ache about the temple, sometimes on left and other times on right. bit drowsy/dizzy, and bit hard falling asleep, which may be more related to respiratory/esophagus concerns, such were not noticed in Ba swallow though.
3) change in stool habit, sometimes more sometimes less, and stool that has been abnormal. doesn't seem as though bleeding is present, seems more bacterial.

There is also some skin rash and nodule (had on forearm w/ and when popped was golden-crust to start then healed, lower leg/ankle abscess, and on abdomen front/back some). Have had no fever, liver diagnostic showed nothing, Prilosec did not seem to help much on gall bladder concern (maybe needs to be more regular, though bone aches can occur more I think), regular blood flow when checked, and so not sure what more could be. Haven't lost weight generally, otherwise just have scratchy throat/some inner mouth sores. All can think is may be coeliac and related to autoimmune, gastritis/H.pylori, or combination? Look forward to hearing if that is a suggestion to the MD for looking into -- hoping for a response soon. Maybe I get some more serology (aside from blood count, as that checked out all right) for gastritis/H.pylori or coeliac done if I go in? Many thanks on the suggestions/insight.