My sister complained of similar problems when she started getting into shooting her carry pistol regularly.
In addition to the advice about leaning foward in your shooting stance, I would advise also doing some stretches before shooting, as you would before any physical activity. And some stretching afterwards as part of a cool down.
NRA Life Member
Big Sister: "You should be sponsored by Allen"
Me: "If you can't shoot good, at least look good walking to the firing line."
Big Sister: "Can you not afford a Pelican? Then buy an Allen gun bag."