ecchymosis....not bruising.....bruising implies trauma......this neednt have anything to do with the blood it self....but the fragility of the capillary walls...vit c would help with that and there are other things....mrsd would be the one to ask about those.....to the OP, have you considered celiac disease?
sinusitis along with your bowel issues cause me to question that for you.....if the docs wont test, doesnt mean you cant change your diet...