I have APS and take Warfarin (INR 3.5 - 4.5). Today I noticed a large bruise on my arm. I don't know how I got it as I don't remember bumping into anything. I've had bruises before (some very colourful ones!) This one feels quite firm and there's a lump beneath the skin. Has this happened to anyone else on Warfarin? I wasn't sure whether to go to Doctor or not as it's not bothering me.