My gelding has the same problem, but he doesn't bleed.
1) Try a fly sheet, fly mask and fly boots
2) Use "wipe n' spray" fly spray, but if your horse has sensitive skin it would not be a good choice, I would then use Branco
3) Use a feed supplement, there are many you can find on smartpak.com for cheap
4)You could try Equi-spot as well, but I have not personally used it
I understand how frustrating it can be! I hope this helps, good luck :)