Hello, It is possible that you may have caused blockage to the lymphatic channels in the skin which is leading to this swelling. This prevents the normal fluid that goes back toward your body from making it to the body and leads to the swelling. Vigorous masturbation can cause this. As long as the swelling seems to be improving, I think you should be okay. But you do have to understand that because I can't examine you, you have to consider seeing a doctor if you are concerned about this.