So I have done most of my riding at school to lose weight, but today was different. At college it is mostly flat where I ride, but I came back to hills which I thought I wold be fine on. I went on my first ride for Christmas break, and although it started out very smoothly, around mile 4 it started going bad. All of a sudden, on a small hill, in the middle of my chest a weird sensation began. It was almost like a pain, but it also just seemed like my heart was being compressed. it continued for another mile so I turned around and headed back, the sensation was there the whole time. after I stopped back home, it continued for 10 minutes of laying down and then was replaced by light headedness and the taste of blood. It took me around half an hour to return to normal. Is this just pushing myself too far? It scared me because I didn't know what was happening. I've lost about 70 lbs since summer and have about 30 more to go (to get me down to 190). Can anyone ease my mind this made me really concerned.