you can take orals. try icing the injection area for 10-15 minutes before you stick yourself, it helps out with the beginner or afraid to stick myself problem
Hydration actually helps a lot with that pain. I always found that the tendon pain was a lot worse when I was not hydrated at an optimum level. That could solve a lot of problems.
hot and swollen ?? is there a red area there?? if so it could be an infection. I have had similar pains though, when I inject in my quads and ride my bike. Hurts like hell after.
Its not surprising if people you see everyday don't notice. It's the people you don't see but every month or so that will pick up on it faster. If your growing and people see you everyday they won't notice, but when they haven't seen you for a while it's easier to pick up because the last time...