Lower left back/butt/pubic area numb from fall onto tailbone. xray is fine. is it normal?

Sacroiliitis?: I see a lot of sacroiliitis - an inflammation of a joint in the pelvis - that often feels like a pain in the upper buttock, and can even sometimes be accompanied by sciatica - a shooting or burning pain in the back of the thigh. It can absolutely be caused by such a fall. Anti-inflammatory we may help (ibuprofen or naproxen) but take with food. Good luck!