Kinda scientific question, any doctors here? (reflexes)

hey guys I'm a mid laner floating between gold 3 and 4, I've always had this problem but hasnt really affected me until now that I'm playing against more challenging players but anyway, my reflexes seem to be completely random. One game i can play like a pro juking, hitting every skillshot, not missing a single cs, etc. And some games I play like bronze 5 trash, and while of course sometimes it can be chalked up to mistakes its seems unlikely that i can go from a game making almost 0 mistakes to a game where all I make is mistakes. And its not like its mental as i'm thinking straight in both scenarios but in some games my fingers just wont listen. This is obviously an extremely vague question and I dont really expect any responses but if any of you guys have had experience with this Id love to hear how you fixed it (if you did) Thanks! P.S Im aware I'm garbage at the game so don't think Im just trying to make up excuses lol