Upper stomach pain, reflux, GERD or something..

Hello Doctor

I have upper stomach pain very often, everyday for the last week.
I had something like this about 3 months ago and it stopped after 2 weeks,
and when I took some Tums.
It's started one day with a pain in my chest right in the middle between my nipples, I thought it was something with my heart, I had it for three days, on and off, when I laid on my right side it seemed to be less painfulPainful menstrual periods.

I don't think it's heartburn because the symptoms are different,
somewhere on the board there is this description of hearnburn: "The burning, pressurePressure ulcer, or pain of heartburn can last as long as 2 hours and is often worse after eating.  Lying down or bending over can also result in heartburn. Many people obtain relief by standing upright or by taking an antacidAntacid (calcium carbonate)
Antacid extra strength
Antacid extra strength assorted fruit flavor
Antacid extra strength tropical fruit flavor
Antacid extra strength wintergreen flavor
Antacid long lasting fruit flavor
Antacid long lasting mint flavor that clearsClear by design
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Clear eyes clr
Clear-atadine
Clear-atadine children's acid out of the esophagusBarrett’s esophagus
Esophageal cancer
Esophageal perforation
Esophagus and stomach anatomy
Esophagitis
Esophagus."

I don't have this, my pain stops after I eat or lay down on my right or left side.
I also take Tums and it stops for an hour or two.

I don't think it's GERD either because I heard that people with GERD sometimes wake up at night with severe heartburn, or even choking on stomach acid, because laying down allows the acid to easily flow back up into the esophagusBarrett’s esophagus
Esophageal cancer
Esophageal perforation
Esophagus and stomach anatomy
Esophagitis
Esophagus. Some people say they have also upper stomach/chest pain that radiates to their back which is associated with acid reflux.
I don't have anything like that, no acid feeling in the throath, no diarreha.

For me it's only pain in the middle upper stomach.
First it was little higher in my chest, between my nipples,
now it seems like it's little lower, or maybe it seems lower because it hurts less when
it first started.
Now just taking Tums and lying on my right side is the only thing that relieves it. I didn't tried any other medication.

When I first got it I though it was something with my heart.
I had it for about 2 weeks, then it stopped for about 2 months,
and now I it started again, the same pain. Now it seems getting worse.

What could it be?