Another thing to check is number of respirations at rest. I still check DS from time to time while he's sleeping. It was usually the first indicator when he was a baby that something was off, if he was breathing more rapidly at rest.
If you have a baby book, it should tell you want the normal rate is, may also give symptoms of rsv -- flaring of nostrils, rapid -- panting breaths, as well as the retracting.
If you have a baby book, it should tell you want the normal rate is, may also give symptoms of rsv -- flaring of nostrils, rapid -- panting breaths, as well as the retracting.