Helloo ... A simple X-ray / Ct scan
would give u the answer, a fresh fracture
will have NO new bone formation at the broken tips of the bone while an old fracture will show a lot of new bone formation and the healing line would be visible.
A hair-line fracture at the time of the accident may have occurred, but it does produce some local pain especially on walking / exercising. It needs only rest as a treatment.
So, now that the fracture is present it does need treatment. Hope u have got your doubts cleared, with best wishes