What causes no stool in my 5 yo?

Background:
From the first bite of solid food at 4 1/2 months we have fought severe, chronic constipation. I have managed to keep her using the bathroom by means of the GAPS diet and enemas. But as of late she has started having no stool. When I give her an enema (without it she will not be able to have a bm) all I get is dirty water. No formed stool. Yet her tummy is not descended. Then for 2 days she had stool, and then back to nothing but dirty water again. This has been going on for a few weeks now. Is there anyone that can tell me what makes stool form, and how to get her to this fairly normal state again? I am trying to not panic, but it is hard. Oh and she also sometimes has strings of mucus about the size of yarn and maybe 2 feet long. She is getting no gluten (tested intolerant) and no starches. Any help will be most appreciated. Tweet