Sounds like you could do with some technique help. My boyf is doing a front crawl course based on Alexander Technique, ie posture and breathing. We'll see if it's any good once it's done.
Anyway, life shouldn't always be about competing. It's not always healthy. Sometimes you simply need to enjoy yourself. I totally agree with the others that you can't compare running to swimming, for all the reasons listed above.
While you're unable to run, I wouldn't get stressed about drop in fitness levels or anything else. Use the time to focus on other stuff!