13 mo Dd's sleep gone wrong. I've just gone back to work. Coincidence?

[Cnix]

She's been sleeping great for ages last two nights awake at 4:30am yelling, screaming, crying and generally getting upset and not managing to go back to sleep. It's only been two nights but now I feel so tired I could cry! I need you to tell me you've been there too and it gets better...

Are you me?! My DS is 13 months and for the last 3 nights he has woken at 3.30-4 and will not go back to sleep. I think he has another tooth coming through but I am knackered.
If I sit in my rocking chair with him he will go back to sleep but the moment I put him back in his cot he gets hysterical. So no words of advice but let's hope that this too shall pass!

My dd is 13 mths old as well! Wakes up screaming before 5 and would not settle again this morning. So tired I could cry! Don't know what's going on... Lets hope it passes quickly

My dd will stay in her cot if I sit beside her and keep my hand on her but if I move even an inch she wakes up again :-(((

My DS has gone from waking at 4, to gradually getting earlier and earlier until last night he woke at 11.30 and I had to take him into bed. I am sure this is a phase (I hope) but it's tiring me out. My friend said if he wakes - going, deal with what ever has woken him and leave. The problem there is that I don't know what's woken him!!