No sleep position is working for me

Every position I try has some sort of discomfort that makes sleeping hellish.

Back:

• Either discomfort in my abdomen, or head/neck.

Side:

• Discomfort in my hips.

My mattress is hard, and i've also been trying to sleep on a wedge pillow which seems to be the best.

But for instance most of the time there's pressure in my abdomen making it slightly harder to breath.

It feels as if some other body part, e.g. upper body is pressing down on it because of the human's natural lumbar curve.

Not even sure if it's internal or what.