Betta Fish: Some advice please, first time fish owner

Hello!! I recently (on sunday) got a betta fish after getting my 10g planted tank set up, filter was given to me by a friend with all filter media he used for a 60g tank of over a year, parameters were all good (using api master kit) but im worried my fish is bloated/constapated. I bought him from a reputable aquarium shop, and did not feed him today (his first full day with me) as he had found at least 4-6 leftovers pellets I didnt see of when I was started to cycle it before i received the filter media from my friend. I was really worried for him and am not sure what to do. I havent found any poop in the tank or anything so I am not sure if he has or hasnt. He did seem very stressed when I acclimated him and eventually put him in the tank and I was instructed not to feed him that day since he was already fed at the store. also temp ranges from 77.1-77.8 throughout the day and night and I am increasing it again tomorrow just doing it slowly.