For maybe 2 weeks now, every time I lean forward even for 20 seconds, when I straighten my back to normal position again, I have terrible lower back muscle pains. It almost feels as if they have been strained just by a simple leaning forward. It takes about 2-3 minutes for the pain to dull. This repeats itself constantly throughout the day. Even if I bend down to tie my shoes, I feel extreme pain towards my lower back once I straighten it again. Sometimes the pain is prolonged. I don't feel the pain while I'm leaning down, but once I proceed to stand straight again, it comes. I'm 16 years old. Any ideas?