I have lower back pain since august 2012 and sciatica and it has been two weeks that i have lower front pain too i am very worried please help?

Reasons: There are many reasons for back pain: arthritis, herniated disk, spondylitis , kidney stones or infection, sciatica among many others. You need evaluation by neurosurgeon or orthopedic surgeon. Your abdominal pain can be related or may not. See physician for evaluation.

Need a workup: Prolonged pain as you describe requires an investigation and a medical consultation, not an internet diagnosis. You need x rays and possibly imaging studies. At you age a pelvic examination is essential. Ask your primary care provider for a referral to a spine specialist. Either an orthopedic or neurosurgeon are appropriate.

Pinched Nerve: Sounds like you have a pinched nerve in your back. I would suggest seeing a pain/spine specialist to evaluate you further to evaluate what level and what can be done to treat you. There are interventional treatments besides medications and surgeries that might reduce or eliminate the pain altogether.