get off the bike now!! Ice and antiinflamitories (motrin). See a good sports orthopedist now! I tore my Hamstring group about three years ago (fairly bad, probably should have had surgery) sprinting to homeplate. I've still not recovered, but for many reasons. I continued to ride my bike, though not nearly as much, and couldn't even think about running ( I was doing half ironman distance races before the injury) and still can't. Doctors pretty much ignore you unless you cannot function during normal life. They don't care that you can't run, ride your bike, or even walk without pain. Can you go to work, is about all they care about. I finally got a second opinion from a specialist and that got me into physical therapy, where I am now and finally getting better, but after almost three years.
Don't mess around thinking you can just work through this, most people can't. You have to give it a real break (months) before it will get better. It can take 18 months for the average bad tear to heal with proper care. Oh yah, stretching is good, but only certain ones and not too long.
Sorry about the bad news, but I wish someone had told me. Swim, a lot, and dont kick.