I’m going through the exact same problem right now; it’s been going on for a month, I’ve had to stop mma training and I can barely keep up with my class, I was able to do 3x3 minute rounds before fine, now I can barely do the warmup, doctors done xray and blood test, checked vitals etc. everything is fine. I genuinely don’t know what to do my life was going really good then this happened for some unknown reason, it’s made me depressed tbh I don’t know what to do.