that doesn't even sound possible! I know you've been running a lot, but that's a lot of calories to gain to result in that much "real weight". I'm guessing some of it is inflammation and other stuff as you body is coping with the injury.
Try not to get too caught up in the pity party, you do have some options. I usually gain a couple pounds after an injury, but when I'm in the right place mentally, I can usually adjust pretty quickly and not get too careless.
Stay positive and think of this as just a break (even if it was totally unplanned) from training. All atheletes have to take a break from time to time. You will come back stronger than ever!