First of all,
I am not a doctor but most of your symptoms i remembered what i went through. Same as you.
My mom told me what it was even after i went to the doctor.
1st advice go ask your doctor. Not the cheap "here take this" doctor. Go to a good doctor who could understand when you say "it doesnt hurt outside but it hurts inside but in a way if feels like its outside".
I always had problems with indegestions and acid reflux. What you are having now is acid reflux. Your asofegus (cant spell) is as sensitive as mine. When you sleep at night i am pretty sure you like to sleep on your right or somewhat around the right of your body. If not, acid reflux might also be caused by your training to lose weight? Sometimes on an empty stomach when you do trainings, cardio whatsoever trainings the gastric juice jumps up and down and touches your asofegus (cant spell). So its irritated causing the tight, mild discomforting filling along the centre almost top side of your chest.
It will most likely start to feel tight, and discomfort when you burp, swallow food, drink warm water, and sometimes from hiccups. Basically anything that touched ur asofegus (cant spell). So the vapor from vapes does make ur asofegus rile up.
How i solved this issue? Dont vape menthol, it makes it feel much more uneasy. There is a medication to lower down your tummy's gastric juice, i forgot what was it, ask ur doctor. Gaviscon helps. Take that, rest from vapes for some time... Cure your acid reflux, take meds. When its ok, try vaping again.
I took Gaviscon fluids, its a white colored liquid med that is minty and very thick. Tastes minty horrible. But it soothes the asofegus (cant spell). After a few days i feel fine. When i vape i am vape happy again.
My mom is not a doctor either. But at times i think she is the best doctor ever.
I've been wrong many times tho