-other non exercise activity varies changing your daily energy expenditure
-you're metabolic rate rises and falls in relation to changes in your intake or hormone levels
-your sodium/carbohydrate intake will affect water retention which will make you gain and lose weight regardless of your lbm or bodyfat levels. dehydration will drop your bodyweight quite a bit if you let it. what are your macros?
-you're fucking something up with your measurements ie. weighing yourself with a full stomach one day then in the morning before food the next weigh in or visa versa or even with different or malfunctioning scales.
-you're not eating what you think you are
none of that shit matters since if you look at the big picture you're still up 22lbs in 3 months, which is great