Could my lower back, hip, and knee pain be caused by neglecting my lower body in my workouts?

I started working out at 14 and I’m 28, it’s always been on and off, about 6 months on 6 off or 6 months on 2 years off l’ve been focusing about 70-75% on upper body and only 25-30% on lower body. Could this be the cause of my chronic pains? I always thought the lower body was way stronger than upper body, so even if I just focused on upper body, my lower body will be able to handle the weight and muscle gain.