M.S.
It sounds to me like teething. My son would wake up a few times in the middle of the night for extra bottles. We'd pop one in his mouth and he'd go back to sleep (unless he was REALLY in pain....). You may find that his sleep goes back to normal in the next week or so... (and then it will happen again in a month or so...) I know some kids get rashes or runny noses (like a cold) when they're teething... my son gets really flush cheeks, gets a little cranky, and wants extra bottles (day and night).
Good luck!