Is this heartburn???

I'm having stomach issues and I'm being tested for celiac disease, fructose test and have an endoscopy scheduled for next week.

I have this weird sensation in my chest. It feels like when I breathe in i get a burning sensation (kinda like you were to breathe in super cold air outside or if you run real hard and long kind of sensation). I don't know what it is but it's weird.

ok i had some what the same except i was having diarrhea everyday.  i was tested for celiac, ibs, ibsd (which they told me years ago i had and didn't)  the drs were ready to give up and send me to another specialist.  they finially tested me for the fructose tube test that they test babies with.  low and behold i was tested postitive for C.S.I.D.  something you are born with.  it is Congrential surcas isomaltase deficiency  a rare disorder the disability to digest sugar due to the absent of 2 enzymes.  i also had a CT artery scan which showed i had Celiac Artery Stenosis (where the artery of my intestines is pushing up against my stomach)  please please keep checking drs don't give up.  with the CSID the dr thought i was too old to have it but tested me anyway, good thing

Sounds like acid reflux.  If celiac and fructose are normal, you may be given a PPI to help with the acid.