I had a spinal epidural and i ended up with air bubbles on my brain is this dangerous and how long will it last?

Air dissipates: A few small air bubbles will dissipate and likely not cause any problems. Larger air collections can cause headaches and pressure: only main caution is to avoid airflight or high altitude for a few days or week. Air in the epidural space rarely has a place to go in the skull, and it is possible that you have intradural (not epidural) intracranial air. Still, this should dissipate on its own.