Re: Almost 5-month-old infant hadn't grown in a month.
Before you freak out over the home scale, remember that if you are going to take them seriously, baby weights should always be done on a professional scale, on the same scale the baby was last weighed on, and in the nude. Otherwise there is just too much chance of the scale being off, even if you check it and you're sure it's fine. My home scale, which is a decent one, always puts me at 5 lbs lighter than the one at the doctor's office. With a little baby, 5 oz would be a lot, let alone a difference of a few pounds.
Another reason not to freak out is that head circumference is difficult to measure. You have to get the tape in just the right position.
The best reason not to be worried is that baby has continued to have good diaper output, and is now at the age where it is very normal for growth to slow down. Breastfed babies tend to gain weight fastest in early infancy, when they do nothing but eat and sleep. As they get closer to the middle of their first year and start devoting calories to motion (reaching, rolling, kicking, pre-crawling) instead of packing them on as fat, it's typical for weight gain to slow way down, and for baby to slip percentiles on the charts.
That being said, I think you're wise to be alert to the possibility that baby has paused somewhat in his growth. The first thing I would do would be to stop letting baby self-soothe at night. 4-5 month old babies often feed several times overnight, and they can take in quite a lot of calories that way. When you suspect a growth issue, the first thing you want to do is to bump up baby's nursing frequency. Don't worry about the green poops: they can indicate an issue but are not in and of themselves a health problem. The second thing I would do would be to stop by the clinic for a weight check. If your baby really hasn't grown in a month, you want to know about it.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"