Really tight pain in my right side after workout

I am 32 years old. In February 2008 I joined weight watchers and in the fall (late October/November) I began a steady workout routine which consisted of rotating weekdays working on upper body and lower body and in the evening an hour of cardio(elliptical) and ab exercises. In the past I have had a weird phobia of treadmills, so I didn't really use them. Last week I decided to try using the treadmill. Now, since I started weight watchers and exercising last year I have dropped 70 pounds. I was never really big on running. Last week I started on the treadmill. I would walk a few minutes then jog for a few minutes. I got to the point where I could comfortably jog for 30 minutes at a time. Monday evening I ran/jogged on the treadmill for 60 minutes at a good pace. I didn't feel like I was overdoing it. Tuesday when I woke up my right side, between my ribcage and waist was in a severe amount of pain. I have taken it a little asier at the gym since then but the pain still really hasn't subsided. Is this common, or did I push myself too hard? Thanks for any input.