2 days ago I pulled my lower back which I strained & was in pain. I'm fbb & decided 2 try wearin my weightbelt. How long can I wear it? It helps me.

Weeks. Belts can help muscle strain pain. They can give some support. It can take 6-8 weeks for the muscle to heal. So you can wear the brace for 6-8 weeks. You should stretch daily though to help promote healing.
Not for long. The main thing is that you visit your doctor for an evaluation, to rule out any injury that may need therapy, exercises or injection. A brace will protect you but will also make your abdominal muscles weak if used for prolonged time. The best abdominal and back brace you have is your own core muscles. www.otwithmd.com.