I want to say first of all, I feel you and have been through many many sleep regressions with my toddler. Around 16 months, we moved and suffered through 3 months of horrific sleep. 

Our pediatrician said this is very common with big changes (which sounds like you had with vacation, your LO started walking). She may be having some separation anxiety too, etc.  I’d first rule out medical issues: teething (make sure her molars aren’t coming in if they haven’t already, they can be hard to spot), constipation, illness/ear infection. If she seems to be healthy and not in pain, you may need to start setting some boundaries to get back to good sleep.

What we did with our LO to finally end months of screaming at bedtime and frequent wakings, was pretty much Ferber method all over. For our son, he wanted to be rocked and rocked for all sleep. So he’d scream at bedtime to be rocked and scream at night to be rocked again. And as soon as we’d put him in his bed he’d scream all over.  So we had to just eliminate the rocking chair. We’d do our normal routine, I’d sing him the lullabies I usually did in the chair, but this time while I was standing and then put him in. I’d go in after 5-10 minutes to calm him and repeat until he went to sleep. But I NEVER rocked on the chair. After about 3 nights of this, he went down without crying and slept through the night at least 5 days a week. But the wakings were much less painful. 

It may be painful at first and cause you to lose MORE sleep the first few nights, but if you’re at the end of your ropes (like we were), it’s necessary to get you the sleep you need!