I get bruises on the front of my legs after doing extreme workouts also. I have never really attributed it to my diet or lack of iron and B12. Personally, I thought it was due to the intensity of the workout. So, I usually ice, my calves and legs after my session.
Just for the record, however, needsize has made a very valid point. I am in a constant battle with anemia. I do not eat red meat --and the lack of B12 blocks the iron absorption in my body.
I guess I never really linked the two together.
It is a good question to ask your doctor.