In my opinion, the best thing you can do when you're feeling envious or taken for granted or whatnot is to be honest with all of your partners about it.... even if you don't know why you're feeling it. That way you can explore why you're feeling it and possibly come up with some resolution for it.
As for the moods and feelings being all over the map.... I can relate. That happens with me a lot. The best solution that I've come up with is to write things down and try to figure out what's happened to cause me to feel negatively about something... a lot of the time that writing for me happens on forums where I can get feedback, but sometimes I do it privately too. I find that if I write things down, I can much more easily look back over time and figure out what's been bothering me than trying to figue it out when I feel negatively one day and positively the next.
So, all in all, I find what works for me is a combination of introspective writing, getting feedback from other supportive people outside of my relationship and getting support from people in my relationship.