Hello , I've actually experienced this problem before for 3 months. I thing I did was actually slowly progressing through the exercise. Cause I realized that my muscle was progressing fast by my tendons weren't and they need 2x more time to adapt. So there was two things I did 1) when I had extreme pain, I will stopped doing workouts for a few weeks or do the easiest progression of the exercise. Like normally I do diamond and normal push ups, I would then change to wall or knee push ups. 2) once I recover after a few weeks or 1 month I would then start all over again with the push up for example and build back the reps then to harder exercises and go back to weighted. And remember to strengthen other surrounding areas cause it could be weak bicep, tricep or shoulders. Hope it recover fast!!

Insane strength man

It took me one month to achieve the pull up. I just hang a lot and was also doing different bicep curls. Now I can do 20. My first 10 reps are chest to bar, idk why but I always think I never reached the bar so I'll just pull explosively all the way

Bro how's your planche now?? Have you achieved straddle planche?

There are a few things I would like to point out that can help you do the 90 degree hold better. 1) have a protracted scapula 2) flex your core So you can stabilize the 90 degree hold 3) Don't arch your lower back cause it'll make it look very bad. 4) Your elbow should be beside your waist instead of above. Overall this could be due to lack of strength. Some ways to strengthen it is by doing pseudo push up focusing on protracted scapula and leaning forward and pushing down. Learn elbow lever as the balancing mechanics are the same just that it's 2x harder.

Thanks for the support Daemon!!!