Yep, sounds exactly like my boy at that age.
As others have mentioned, I think there are lots of possible reasons. Being distracted during teh day and making up for it at night; separation anxiety; upset tummy (sometimes stopping solids helps at this age); teething; some other stuff, who knows!?

Like Kelebek, I think the best thing is to just survive. Do whatever works best - co-sleeping certainly helped us too. And I was working full time back then too, so I totally get how you're feeling. It will get better, you just have to ride it out. Good luck.