Hi
Since there are no muscles covering the medial side of the tibia, the kick could have easily bruised the bone. bone contusions or 'sub periosteal haematomas' can persist for several weeks to months or even years (depends on the level of injury to the bone). As stated by you, bony contusions don't cause pain on weght bearing however they cause pain on palpation since you are directly touching the injured area.
I would continue to apply ice on the area in order to reduce swelling and pain. This also helps speed healing. I usually supply patients with glucosamine to help with healing as well.
However, if pain will remain constant, I would check with a doctor in order to rule out any fractures.
Regards