Pebbles Stopped Walking?

Hey my fellow Bohemites, my horse, Pebbles, suddenly stopped walking. He now arrives in a glitchy manner when called, and then when I mount his strong, yet soft back, he doesn’t move. I have been playing the game for about a week and had no issue when walking or galloping with the grey-maned beauty up until now. Anyone having the same issue?

He has fallen into depression.

Alas poor Pebbles, I rode him well.