sometimes ,when u take a lesson... u're ingraining the new swing ... on the range . u're more relaxed and also remembering the lesson in your head.. but on the green , u probably forgot or was focusing on the one aspect of your recent lessons but forgot the other fundamentals...

for your short game , it's probably one of the most personal part (except putting) in the sense that it's mainly about feel... so that doesn't go apart so fast , but for the irons , woods and drivers ... that's very dependant on the swing that u're having ..and if one part of that swing is out , or adjusted by your "lessson" , i supposed it's possilbe to cause your current situation ..

think abt it and see if it relates to you. after my first lesson , i ballooned from a mid 90s ~ 100 hitter to 110+s .. after 8 lessons over 3 mths , i'm back to the low 90s again ..consistently , almost breaking it.. that's just my personal experience..