pain under left rib cage, what could it be??? worried

Hello everyone,

I have pain in my upper abdomen, on the left side, right under my rib cage.
Iseldom feel the pain, so although it has been there since at least 1 year or so, I have never paid too much attention to it.
Now that I am pregnant, the pressure from my growing belly makes it more noticable so I decided to get it checked.

The pain is dull and I only feel it when I bend over my legs in a sitting position, as I do when I practice stretching exercises. Especially when sitting legs apart, and bending upon my left leg, I can feel a discomfort there, like a "knot".
I also can feel some pain when laying down and pressing firmly on the area.
it is a very small area, I would say a square inch above my last left rib.
I do not notice any correlation with meals, nor do I suffer of heartburn more than occasionally ( it is quite normal when pregnant).

Do you think it might be stomach ulcer?
I was worried about it being a pancreatic issue?

Thanks for your help