Background: two months ago I went to the beach to train. The sand had been recently "tilled" to clean it, so when I did my push ups and other exercises that used my hands as support, my fingers would sink in the sand, their position was like when you are doing push-ups on your fingers, but with sand all over them. I had muscle pain they day after; I considered it appeared because my hands were exerting themselves much more and using more muscles to stabilize my weight than normal push ups and what-not on hard ground.

The same pain (on the hand muscles, not the joints) has been appearing for the last month on and off, and it's taking its toll on my training:

- I can't up the weight I lift because my hands start hurting and can't keep the grip, even though I'm not lifting more than 8 months ago, I'm not adding weight every week, and the rest of my body does keep up with what I'm lifting no prob.
- It's harder to train BJJ when you can't grip. We may be drilling compliant chokes, and I can't exert force as fast as before because my hands hurt and can't go beyond a plateau of what's like 50-60% of what I can usually do. When rolling is even more noticeable, since I cannot pull or hold on with full force.

I'm not training more than 8 months ago, I'm not lifting more than 8 months ago, I haven't been ill, nor suffered any hand injure ever, I keep a balanced diet except for fish oils and Omega-3 that are probably below recommended. I know training BJJ can make your fingers hurt, but I always thought it was the joints not the muscles...

My pain is focused on my palms most of the time, especially between index and thumb when I lift. When I do BJJ it spreads beyond the knuckles up to the proximal phalanx but never beyond.

TL;DR: my hands muscles hurt when I grip something. What do. Also, your own experiences with hand muscle pain.

Thanks in advance.