To stretch your quadriceps at the hip, the idea is to do the opposite movement to flexion, i.e., extension. You can perform extension moves at the hip while standing, lying on your side, lying prone (on your stomach) and kneeling. Even basic stretches done at a pain-free level where you can feel a small bit of challenge, and that are held continuously for approximately 30 seconds may translate to better posture and less back pain.
Meanwhile, it’s extremely common for non-life-threatening low back pain to be alarmingly severe and persistent — to have a loud bark! Your doctor may not appreciate how true this is, and may over-react to all persistent low back pain, even without other red flags. In most cases, you shouldn’t let them scare you. Being “freaked out” about persistent back pain is the real threat: it can make low back pain much worse, and much more likely to last even longer (a tragic irony).
You can strain or tear one or more of your hip flexors when you make sudden movements such as changing directions while running or kicking. Sports and athletic activities where this is likely to occur include running, football, soccer, martial arts, dancing, and hockey. In everyday life, you can strain a hip flexor when you slip and fall, for example.