Lower back pain? hurts only when i bend over or sit in certain spot, or when i straighten up. have had this several times what is this?

Muscle strain,lumbag: Typically back pain that worsens with movement in a young person is consistent with muscle spasm or lumbar strain. However, it is still appropriate to have a consultation with a PMR or sports medicine doctor and they will complete a physical examination of your spine.In addition they will also consider the possibility of other diagnoses that could be causing your symptoms such as disc disease.