I was having some major chest pain when I started.
The vibration from each step was a little bit painful. After about 15 minutes jogging it went away completely. Now I'm back home and I feel way better than before.
I seem to have stretched my insides where I was having pain and cleared it up a bit.
Do you know the cause of your chest pains? I know that when I drink caffiene I get muscle spasms in my chest. It could be completely unrelated to your situation.
Yes, I got into a confrontation with my flatmate on the weekend. I ended up "chest-bumping" him really hard. Seemed to have caused an injury.