Left hand technique problem and hurting - thumb muscle vein slightly enflamed.

[Ganky]

I've been playing 3-4 hours a day recently and my left hand has been hurting quite a bit , I find that whenever I'm playing, my left wrist can barely ever be straight, especially when playing chordal fingerings.

Once in a while, the vein going around the thumb muscle will feel like its throbbing, and I have to stop playing for a sec

Should I play for smaller slots of time, and muscle will build up over time, and stop the problem, how do I play without having to bend my wrist to almost 90 degrees?

Some help would greatly be appreciated - going to just work on right hand technique today : )

[Fergie Fulton]

I play for 30mins twice a day. Each one of those sessions takes an hour and a half of my time which includes warm up, the 30 mins and warm down. I know thats a luxury because my job to play bass these days.
As i will say...again.. injuries are mainly caused by over-use and miss-use in the absence of trauma, go and see a medical profesional.
As i know nothing about what you do, all i can suggest is to rein it all back in and start with a specific practice programme you can time and monitor. May you have your week split and each day addresses a part of what you are doing now on its own.
If your working on dexterity make that one session, then stamina the next, then supplness and fingering the next, and so on and one session at the end of the week where you apply it all to see the results of your work.
Work with an instructor for an second opinion, looking at it from his point of view. Try some sight reading and ear training, stretches etc there is so much you can do that does not involve playing to improve as a player.

[Ron G]

Ganky, I switched to using 1-2-4 fingering system:

The 1-2-4 fingering system allows us to keep the hand relaxed and comfortable, particularly when playing in the lower regions of the bass where the frets are farther apart. Start with the pad of your thumb in the middle of the neck; make sure it doesn't stick up over the top. Thumb is positioned between the first and second fingers.

Place your first finger (Index) 1st fret of the E string, second finger (Middle) on the 2nd fret, and fourth finger (Pinkie) on the 3rd fret. Your 3rd finger (Ring) can help the (Pinkie).