This has happened a few times but I have been having throbbing, pulsating, pain in the lower part of my back and from side to side it only lasts about a min or so

It could be any number of things. Since we can't see you and don't know your medical and activity histories, we just can't diagnose this. Please go to a doctor and get this checked out. You don't want it to get worse and debilitating.

To find out what's wrong, you'll probably need a scan, to check what's up, it's no sweat, but depending on what scan CT, or MRI, I found the MRI a bit scary, so they gave me some Diasapam, to calm me down. Hope this helps... GOOD LUCK..