Lo is 3wks20days and fully fed on formula, recently he has been drinking less, he wakes up and doesn't really want to drink...he used to drink 110 to 120ml every 3-4 hr...now sometime he can finish, sometimes drink 60-80ml n sometimes over 5hrs he also don wan milk...it became so random till i dont know how to make for him. Could this be a growth spurt or teething or maybe he isn't feeling well?