Have I broken my leg, what's the damage?

[Uzi]

Hello, well earlier whilst I attending Physical Education outside we were playing Football. I ran in to gain the ball although I collided with another opponent. The opponent fell backwards and hit the floor whilst I didn't take much note of what had happened and continued playing. After about 2-3 minutes I had a large amount of pain coming from gastrocnemius (lower leg muscle). I couldn't continue playing on the pitch so I thought I would remain in goal for the remaining time through the game, I was limping throughout the match and could barely walk and struggled to run.

After the match I continued on with the rest of my theory classes and managed to walk without too much trouble, I didn't bother getting it sorted during my time at school. I just limped on my left leg through the whole day. After school I had the same problem continuing, by this time I knew it wasn't a minor injury because it would have been healing automatically, it was continuing to get worse during the day.

Right now I can barely walk, doctors are closed and I'm not sure if I want to head over to Accident & Emergency because I'm not completely sure if it's something serious or not. If anyone has experienced the same problem then be sure to let me know what the damage is and if it's a serious injury rather than something minor. I was planning on going into school for the last day before the Halloween break although I don't think I'll be walking for a while.

TL;DR- Injured left leg whilst colliding with someone in a Football match, didn't take much note of the issue. After school suffered from large amounts of pain and whenever pressure is applied to my lower leg it's very painful. Even the slightest of movements can inflict damage.

EDIT: Forgot to mention there's no bruising or swelling forming, it's been giving me pain throughout the past 8 hours.

Thanks in advance SupportForums.