Hi Dawn!

Welcome! This is really a good site, you can learn alot. When my daughter first diagnosed, I read EVERYTHING on this website probably 20 times or more! I was giving my daughter, who is 2 1/2, weighs 36#, 500mg of arginine per day. I think it did help, as her poops became even more normal. Unfortunately, about 2 months ago, she decided she didn't like the taste (we still put everything in baby pears b/c she can't swallow pills yet) and has refused to take it. I'll admit, the powder in the capsule does taste awful. But, with an older kid, its probably easier.
Hope can tell you more about doses.

Good luck!
Kim