Hi,
Hair-line fractures can cause pain also.
I highly suggest you go to a doctor, have an X-ray done, and find out what to do.
I do wish you the best, and hopefully, it will just a strained muscle, not an actual fracture.
yes it is possible to fraxture your leg and still walk on it. If you think that you may have fractured your leg get an X-ray. Sometimes it may take a few days for a Fracture to show up on X ray. I have had athletes fracter there leg and walk on it for a while, depending on the fracture, and location. You might just need a walking boot. But its important to see a doctor to get an x ray.
It is possible to be able to walk, although not normally, with a minor mid shaft fracture of the fibula, since the fibula is not a weight bearing bone. The tibia is.