It totally
when stuff like this happens! It's hard enough to lose weight and maintain our weight loss without fate throwing injuries at us.
But lifechange is right--you are so close to your goal and you've shown such strength and discipline to get this far; you'll get through this somehow. It's just going to take some adjusting.
First go see your doctor, as Jayell suggests. I think I'd do that before icing it or anything else (other than take some Ibuprofen, stay off it, and keep it elevated), since you don't know what the pain is and it sounds like it could be more than just a soft tissue injury. While you are with your doctor, pin him/her down on what exercise you can do--swimming? bicycle? Does your gym have a rowing machine or one of those arm thingies (it's like a bicycle for your arms). Or maybe upper body strength training? There is a woman who has been coming into my gym lately with a walking cast on her foot and entire lower leg; if she can find a way to exercise in that thing, maybe you'll be able to find some exercise you can do as well. But see your doctor before doing anything of these things.