I was you seven months ago but my reason for staying in was different. I was too embarrassed to work out or even walk in public. So what I did to get started was to turn on my favorite music or podcast and just do laps around my house. I know to anyone else I would look ridiculous since my house isn't big but I did it anyway. I started with just five minutes at a time a few times a day until I built up strength until I got to thirty minutes. By then I was ready to go out and walk. Maybe the same could work for you only with getting back to your normal swimming routine? Also? A little muscle soreness and discomfort won't kill you. It just means that you are making progress. Best of luck to you.