I got a b12 lipo shot about two months ago and at the injection sight i got a knot followed by numbness & pain...will this work itself out over time ?

Possibly/probably: Sometimes there is more trauma than expected from an injection. The site becomes inflamed and as it heals, firmer scar tissue is laid down. This process may be slightly painful. It can persist for a surprisingly long time ... often a year, sometimes even longer. But almost always, as time passes it becomes less and less symptomatic. Hope it calms down sooner rather than later for you. Stay well:)