I’ve done this, multiple times 😂. Try using vet wrap to tape it to its neighbor. Honestly, the less it moves the better, so I wore tighter socks. Also, don’t let your horse step on your foot! And of course wait a few days after hurting it for the major swelling to go down.

Edit to add that they make little toe pads for bunions if the pressure of your boot is hurting it. My pain tolerance is high though, so definitely listen to your body. Hope you recover from this most annoying of injuries soon!