Yeah you defenitely always need to stretch before you workout or run. And taking a jog helps loosin up the muscles too. Your probably just sore because your not used to exercising that much. I remember doing track in high school, the first week of the season was "hell week" where we had very hard practices the first week, I was always out of shape at the beginning of the season and I would limp everywhere, and I know what ya mean, stairs were the worst! In a few weeks you will probably be feeling better and you wont be hurting after practices. Dont forget to stretch, if all your doing is playing volleyball, you could probably get away without stretching, but do it anyway, it cant hurt.