Can low back pain affect your knee? i find that if i sit my low back hurts all the way to my knee? please explain thanks for answering all my question

Yes: Discogenic and si joint pain can refer to knee l4-3 nerve irritation can refer to knee.

Hip vs back: First, make sure not a hip problem. Pain with sitting, getting up from seated from groin to knee suggests a hip problem. Movement of hip will also aggravate. A disk problem will usually cause pain past knee. But, a less common disk problem at l2-3-4 may cause pain radiating to front of thigh to knee. It may require a doc visit to confirm. X-rays/mri also may help if still in question.