I'm having lower back pain and i'm feeling unstable sometimes when bending or even when walking , i feel like my back just gives out ?

Try conditioning: Sounds like there may be some muscular weakness in your back. Try going to your family md for eval and a referral to physical therapy to strengthen your low back or look for reasons for instability.

That's a problem: When you have a problem with your lower back its not unusual to have your leg feel like its not there or to give out on you. If you irritate a nerve its like flipping a switch and cutting the power to your leg - it goes right out. It can be caused by a slipped disc, arthritis, or instability between two adjacent levels. It probably needs to be evaluated with an MRI to see what's going on.

Several options: If you have not tried core exercises to strengthen your back (tummy and back muscles), try that first. Regular aerobic exercise is also important. If you still feel unstable, see a spine specialist for examination and assessment.