wound on betta

hey guys. this is my mom’s betta, juan. he’s her pride and joy and she’s had him almost 2 years. he’s in a 5 gallon tank with about 4 mystery snails. she said he was in his hide with one of the snails and she thinks the snail attached to him but i doubt that’s what happened. i’m thinking it’s more likely he was trying to get out and got scratched up. he’s looking lethargic obviously, she thinks he’s gonna die but i think there is hope. she is pretty good about water changes, she did one a few days ago. any advice is appreciated. i’ve read a little bit and looks like people are saying frequent water changes and aquarium salt can heal him. she’s gonna call a fish doctor place near her tomorrow. thanks x