6 week old constipated or something else??? new mom?

Yes, it is possible for him to be constipated, and that would certainly make him fussy. I know it can be hard to tell when you're feeding, but is he still drinking a normal amount? Does he still have a normal amount of wet diapers? Most importantly, you need to be sure he's staying hydrated. It's actually normal for fed babies to only poop as little as once or twice a week, but if his bowel movements suddenly change (like it seems they are), or if he seems really uncomfortable you might want to call his doctor's office just to check. Does his tummy seem bloated? Is he bringing his knees up to his tummy when he's crying or fussing? If so, he probably is a little constipated and that does hurt. :( If you're concerned, or if he gets increasingly uncomfortable, I'd call his doctor just to be sure. Try not to worry though, it's actually pretty normal for the little guys to have a tummy ache once in a while.