2 days ago the anterior of ankle along the fibula started to hurt for no reason, very little swelling, im worried it could be serious... Bone cancer?

Doubt it's cancer. Very doubtful it's cancer. If you are active you could have tweaked it . If you pronate that could cause it, or it could be a number of things. Try rest, ice, compression and elevation and if it persists see a foot/ ankle specialist.
Sprain. Too soon to talk about cancer. Rest, elevate, ace wrap, and take Ibuprofen (if you are not allergic to it).