One year old baby question

So idk why but this happens every other night one night will be good and he will sleep good and the next he is fussy In His sleep and wants me to rock him then I lay him in bed and he will wake up I try to lay him with me he wakes up he will only sleep in my arms but there is days where he sleeps in his bed good he still wakes for milk tho is this normal why dose he wake up fussy every other night we do the same exact sleep routine and time just some days he sleeps and some he’s fussy any tips ?????? Or any idea why his happens