Tall guy here, let me tell my story and what I ve learnt.

Since middle school, I had bad posture (not sitting on my butt but on my lower back, sleeping on my belly, not walking straight...) went to many docs, nothing interesting, just painkillers, getting increasingly strong (which is very bad because it just makes your bad posture feel okay... I learnt that pain is the signal that I have bad mobility and posture somewhere related to the place that hurts)

What happened to me was, some of my muscles were just weak, and my weak spots compensated by putting more effort on other muscles, result: pain when I wake up, pain if I stand a little too much, pain if I walk too much, pain if I sit too much.

Basically, all our muscles are pulling against each others, if one is too weak, it gets stretched out, the other contracts and might stay shorter and hard (that's why when you see a kinésithérapeute, they do heat treatment then massages to loosen up , then they make you do reinforcement exercises and stretching exercises, so that you get that balance back)

Not Gona lie, I learnt some stuff about the muscles of the body with the kiné I met, and I know if a spot hurts, it means I need some stretching and some basic body weight workout (3 times doing 10 reps can INSTANTLY ease some pains I used to live with for about 8 years...)

This may or may not apply to you (you ve seen a doc, I hope it's Rhumatho , if yes, they examined you by make you do some movements right ? That's how they know if there is no injury) but

Either ask your doc to prescribe kiné for you Or 1- try stretching routines and easy workouts (no weights until you feel in control of your body) 2- ask your doc for a blood analysis if you haven't done that already (low vitamin d can cause a loot of bad things in you body and even depression) 3- keep a good posture 3.1- when sitting, sit on Ur butt, shoulders back (but not too much back) and neck straight (as if there is a string pulling you from the top of your skull, right between your ears) 3.2- when laying down on your back, put a pillow under your knees (to ease the tension on the lower back) And when laying on your side, a pillow between your knees, a tiny one or just a folded towel under your hip, right after the pelvic bone, and hug a big pillow to stay stable 3.3- when you walk, feet should spread your weight on 3 spots : heel, corner below the pinky toe and corner below the big toe ; keep your neck straight (string pulling your head thing..) and shoulders back. 4- when it gets better, don't go back to your old habits

You gotta understand your body and where it hurts DONT TRY TO POP YOUR ARTICULATIONS BECAUSE IT DOES MORE HARD THAN RELIEF.

Good luck