Try this sometime: vent the bottle with a large 18g pin, boil some water in pot, remove pot from heat, place vial in hot water, swirl contents of vial every couple of minutes, then place vial back in the hot water, reheat water and repeat a couple of times.
Many of you already know this trick, but it might help someone. The idea is to warm the solution and cook off some of the BA which is likely causing the knot & pain. I can tell you it works for me. Often times just warming the solution prior to filling the syringe is sufficient to allow better absorption and less painful injection sites. I heard of guys using a hairdryer to warm the vial's contents, but I just sit the vial in a bowl or pot of boiling water & swirl the contents every couple of minutes.
Another tip: riding a bike & high rep activity utilizing the muscles in the affected area will help things get back to normal more efficiently. Squats, leg press, lunges, biking, running, etc...