Hi, I'm a 18 year old girl, with no medical history whatsoever (except the fact that i was born 1 month too early, but that never had any effect on my life). I'm 5' 6'' and around 140 lbs

I've noticed lately that i often experience a sort of dull (?) pain in the center of my upper chest, where the ribcage kind of connects at the top. I don't know if ''dull'' is the right adjective, but it's like when i breathe it will worsen, and be really uncomfortable, like there's not enough space for my lungs if that makes sense.

As an example of this, sometimes i will be resting on my stomach in bed when all of a sudden, with every breath i take, i feel a discomfort in the center of my chest, and it gradually transitions into a light pain. It isn't super painful, it's more uncomfortable than anything.

I don't know if this is related to this, but the other day i went hiking in a mountain and i was out of breath at the very beginning of the trail, which i don't think is normal for someone who works out pretty regularly like me. When I say out of breath, I literally mean I was having a hard time breathing and the air was burning my throat. Everybody on the trail seemed fine.. When I was resting after the hike, it felt as if my heart area was numb, just like your legs feel after a long run. I don't know if my lungs were the problem, or if it was my hearth or what, but I'm pretty spooked out.

I also feel a stabbing pain in my head when i bend down sometimes, it happens really randomly and even when i bend down really slowly. Again, I don't know if any of these things are related or not.

Sorry for the lenght, I'm just really confused and scared to be honest. I don't know what's going on