I'd try and figure what it is that's causing the upset... could be something as simple as a tree branch and a street light coming through the window and freaking her out... could be a nightmare... could be she heard someone else's grama died... or could be another form of separation anxiety.... if you're a stay at home then bedtime would be the greatest separation she knows.
No way to know unless you ask and she's able to tell you... it'd be a shame to spend months, or years, going through this over a tree limb... when you could just trim it up... not just for you, but DH at work.. and kiddo being freaked... I'd give trying to figure out what's going on a shot. If she can't tell you... maybe ask those she's seen recently, if any. Maybe try going into her room at night and plopping onto the floor, or 'her line of sight' and seeing if anything looks "scary"...
Just some ideas. When I was nursing I'd go in for feedings all hours and sack out, and if the kiddos were sick (rare)... other than that we were very lucky that ours pretty well stuck to their beds. But, I imagine that's skewed a little, it's been 6 and 10 years since ours were two. Kinda like how during childbirth mom is cussing but afterwards it's totally worth it oh look at the cuddleumpkins... time can soothe a lot... especially a little thing like sleepless nights so take that with a grain of salt... and maybe some Ibuprofen.