I'm having back pains, what could that mean?

I am a 16 year old girl and for the past four or five days I have been having a really bad pain in my lower back. The pain is also occurring in the side areas of my lower back. Sometimes my upper middle back will start to hurt as well. My front abdomen below my belly button has been hurting too. I feel fatigue and sometimes different joints feel weak. I have been having head aches on and off. What do you think the problem might be and do you think i should go see a doctor.