Confused, weird feelings

So lately I've been having some very weird feelings... I recently went no contact with an ex I was still in love with (about 2-3 months ago) and I've been the happiest I've ever been in that time oddly. Nothing could bring my mood down, everything was going great! Until about a week and a half ago... A few things happened in a row that weren't even THAT bad, and my mood ended up slowly slipping down. Ever since then I haven't been able to pin-point what exactly is wrong. I've also been thinking about and missing my ex for the first time since we went no contact. The feeling I have is best described by just completely not knowing what to do with myself. I constantly feel like I need to be doing something important or anything else, no matter what I'm doing. Almost like a constant anxiety, and I can't stand still (I've never been like that before - I've always been completely fine with just relaxing and not doing anything on my down time) I've been able to put on a show of a good mood and happiness the past few weeks, but it's just that - a show. Before that, I was genuinely the happiest I've ever been.

There's a new guy at my work that I'm somewhat attracted to, but I haven't really spoken to all that much. I don't have feelings for him or anything like that, but I've been having nonstop dreams about him the past couple weeks. It's very strange, as I don't normally dream about people I know.

I guess what I'm asking here is, has anyone else experienced this "don't know what to do with myself constantly" feeling? How did you deal with it? And do you think this has anything to do with my ex or this new guy at my work that i'm dreaming about?