Hand gets shaky while aiming in CSGO

I've been playing shooters (mostly TF2 and PUBG recently) for 5 years now, and have been trying to get into Counter Strike. But whenever I practice my aim or play competitive, I have this strange thing that happens: I move my crosshair near the target, and when I try to adjust my aim, my hand just tenses up and freezes, getting shaky and I can't properly adjust my aim. It's especially bad when spraying, it takes physical effort to move my hand.

Have any of you ever had something similar? If so, how did you get past it? Can I practice in some specific way to get rid of this? (It's not anything medical btw).