Hello all,

Since a few days I have a trouble when I sit.

When I sit down, and I'm straight, I feel the bones of the lower basin (between the buttocks and thighs) undergo pressure, what bothers me and prevents me from concentrating.

I sit like I always did, I tried to change my posture, but nothing changes.

I had this one time but don't remember how it vanished.

Does someone have an advice, and/or can explain what's happening?