Betta Fish: Lost my boy last night :(

i still dont know what happened. last night he was completely fine, i walked past his tank 5 minutes later and he was laying on the bottom. i tapped him and he flipped out doing barrel rolls and swimming upside down so i put him in his quarantine tank and he didnt make it through the night. im wondering if maybe he hit his head really hard on the glads? all ither fish in his tank are completely normal. im just trying to figure out what went wrong. Rip bill ❤️❤️