What you're experiencing now is not unusual. During chelating, symptoms often go away, only to return temporarily. For me this often happens during a round of chelating and stop when I take a break.
I'm a big walker, but, even when I took marathon walks, I never noticeably lost weight. I suggest that your weight loss is likely related to getting the mercury out (and probably especially related to the effect it has on the yeast in your body).
I wrote before that it took me 6 months to feel real improvement. It's a long, slow process, but it's clear that you've already made progress. Keep it up.