QUESTION about lower back pain?

i have a sharp pain on my back and it hurts really bad and it hurts my and my backside upper thigh.. it hurts really bad and it started like 3 days ago everyday getting a little worse.. i would say my pain is like a 7 out of ten right now.. especially if i try to stretch while im sitting down and try to reach towards my toes with my hand... it hurts more wen im sitting down than wen im standing up ='( what could it be? i havent gone to the doctor yet and i wont be able to go til monday please help