This is odd to me, but he seems sad. He could feel like he’s missing you or your mom. Horses can get depressed, even jealous. My gelding wouldn’t let me touch him for almost two weeks and would pin his ears and strike at me when I came near him after I got my new mare. I just needed to spend a bit more alone time with him and then slowly bring her in. It doesn’t sound like a health problem, but I could be wrong. Maybe he’s just feeling a bit homesick and it hasn’t shown until now. This is just my best observation, hope I helped!
No horse is incapable of learning- riders are just incapable of teaching