My 9 week old son poops once every 10 days. yet, he's pooped 3 times in the past three days, 1 for everyday, andhis poop has been bright green/watery/stringy. could therebe a problem?

Can be normal: A breast fed baby can have a small smear of poo with every feed or a giant blowout once every 7-10 days.Normal volume is about 1/2 cup/day at 9wks. Color variation through various shades of yellow to green are normal. See the dr if concerned.

Change in BMs freq.: Any change in frequency or consistency of bms is considered diarrhea. If he has stringy stuff he probably has mucous. You should have him checked out byu your pediatrician. When he had bms evdry 10 days, was he constipated or was his bm still normal?

Probably ok: Frequent, loose, sometimes greenish stools in infants indicate "rapid transit" of stools that can be due to host of issues but unless he is not eating, having fever, appearing ill may resolve with just observation or care with the diet if other foods have been introduced. If adding new foods this may be part of the problem but not necessarily mean they have to be stopped if this problem resolves.