Hand feels broken from playing kovaaks csgo overwatch etc

Starting back playing PC on fps games.

Literally after about 5 days of about 3 hours total play time each day my hand specifically my fingers tendons and a little bit of my wrist feel absolutely drained

I use a fingertip grip and for the first few days everything felt great I was hitting my shots felt super accurate micro adjustments felt super fun was hitting silly shots in csgo and having a great time

Not sure where it went wrong or why but everything just feels so laboured now what felt super easy now feels slow and impossible like my brain and my hand short circuited aha

Not really sure of the problem i play pretty low sense I have a fast pad and fk1+ c thinks like 80 grams decent fastish skates

I play left handed and I only switched like 5 years ago from right hand and I've played on and off so I actually don't have a ton of experience in fps games or just general mouse usage like I guess everyone or most browsed with a mouse X amount of years before aiming Not everyone of course but alot so maybe it possible I've created my own bad habits I've actually notice this trend I'd play too much go from aiming really well thinking I can build on this then ending up watching everything decline get tired and then I'd find something to blame I think because I've started to use finger tip grip I'm much more able to see its hand fatigued but in the past I couldn't really using like a finger claw with no finger vertical movement.

Not sure if its my lack of experience is forcing me to force my fingers instead of passing some of the stress to my arm and wrist like I've never just played a chill gaming like 50pct effort running around its always been like intense fps csgo overwatch

Play with decent posture elevated chair height arm extended literally wear a sleeve so not much friction

Just a bit lost I went from getting called out for cheating to feeling like someone jumped on my hand while I slept

Anyway any advice would be awesome

21 by 11 hands using a fingertip grip with good finger range of motion