maybe you are pumping to much or the pump is not sitting correctly? your nipples shouldnt be bruised, and i can imagine that would be pretty painful
why has your milk supply gone down? are you still putting your babe to the breast or just feeding him pumped milk?
as far as healing the bruising goes, you need to find out why you are bruising first before it can be fixed. putting a slice of raw onion on the bruised portion will heal the bruise quickly...it sounds awful, but it works fast. wear the onion like a breastpad, just wash before you nurse or pump again, and replace afterwards with a fresh slice. i bet the bruises will be gone in less than a day.
i hope something helps