The usual severe cervical headache, for me, also causes the numbness of half or less of the tongue, and
sometimes the same side lip or jaw and
shooting pains down one dermatome in
the upper arm, or stabbing eye pain on the same side.
A way to check if it is possibly the cervical headache: Lie on your back, have someone very, very slowly move your head (ear toward shoulder) without turning your face toward your shoulder. Have them move your head from your left to your right.