if your Doc tells you, that your body is fine, try to relax more; go slow, but go!
I am bilateral, both hips in the same surgery, not sportive, 56 and my BMI is 30. I used both crutches for 2 month and then suddenly noticed, that I only used one inside. I wanted to do more, carry more things........
the next phase was to go outside with only one crutch...... and so the weeks went by. now I am 7 month out of surgery and walk perfectly without any aid since 8 weeks.
so what I want to say is: its a mind thing also.
it is good to be careful but it is not good to be afraid. if you feel unsecure or afraid the whole body tightens up. you do not walk perfectly upright, you bend down a little. then the joints have a "wrong" load, then the muscles work under stress.......... and you are in a bad circle.
the only way to walk upright again is to let go of the walking aides.
sometimes, in the first weeks I have had pained/crumped muscles also. when that happened, I stood upright, lessened the weight bearing on the crutches and started a "hippy-shake-dance", that helped a lot!
so, greetings and take care!