@toukaoone - i have no idea... sounds pretty serious, like ask a physical therapist/MD serious
conventional wisdom says dynamic and static stretching but i assume you've tried the majority of conventional wisdom if the problem is as dramatic as you say
any fitness/strength training routine i'd recommend starts with squats and deadlifts which are certainly impossible the way you describe them
i suppose it's possible that you are using weird form when squatting (or trying to do unweighted squats where your trunk is upright) - have you tried doing barbell squats?
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Je suis toujours serieux. D'autrefois, personne ne me penserait serieusement.