Need opinions on this

Hello everyone!! So, maybe this isn't the place to post this, but I don't know where else could something like physical health go since I'm still getting used to this platform.

Anyways, since I was a kid I had these weird pains on the left side of my chest, I can't really describe them, but they were really but it was a strong, stabbing pain that made me stop what I was doing for a few seconds and take a deep breath. When I took a deep breath the pain grew, but immediately afterward it went away. Over time it became less and less noticeable, only once in a while it came back like a strong stab.

For a few days now I have been feeling discomfort in the same area, the left side of my chest. Sometimes it feels like throbbing pain and I have to breathe to make it go away, or I try to burp to see if it's gas. When I breathe very deeply, a minimal pain is felt, as if it were barely visible, also when I laugh. At night, it has happened to me that being on my back made me uncomfortable when sleeping.

The best way I can picture it, It's like I have something under my left breast, right underneath, I don't know if it's an air bag or what. What do you think it could be?

My sister who has studied medicine, told me it probably was just gases... But I just want some more opinions