Possibly?? What possessed you to sprint with weight, you nutcase?!
Okay, first off, I have to say that you runners are completely whacko.

Second, get it checked out to get an accurate diagnosis. If the injury is muscular and there is indeed a full or partial tear, it will need recovery and I don't advise attempting the marathon. If you attempt the marathon you could easily put yourself into rehab for months. Even walking the distance would do it in. With rest, however, it should heal relatively quickly. BUT if you've torn a patellar tendon you are bigtime screwed for the next few months at least.
On the bright side it could be a relatively minor injury, and you could be recovered in a week. Either way I would give it several days' rest, and take that time to visit the doctor for an accurate assessment.
Please don't try to muddle through this without knowing what it is. Otherwise you'll spend your summer paying $60 an hour for medical rehab from someone like me.

But worse, you'll spend much, much longer not being able to run if it is, indeed, serious.