Afte running, the glute, thigh and leg muscles should relax. If they tighten up instead, that indicates muscle fatigue. The muscles tighten up to compensate for the fatigue.
The cause is the pulling or twisting of a nerve or muscle while running and the pulling and twisting that occurred remain uncorrected when the muscles were supposed to relax after running.
Give the running schedule a rest, take a very hot shower, use muscle rub, allow the glute muscles to relax.
One indication that the nerves and the muscles of the glute are twisted is that one would feel a pinching or a twitching sensation in the toe. This sensation can sometimes be induced by letting someone sit on the glute.