After vowing never to have dd in bed with me, have had to cave in a few times....so we now do a mixture of ignoring, which is sooo hard, and taking into our bed.
She too was always a brilliant sleeper up til just over 2, then we started getting disturbed nights. The first time it happened was for about 6 weeks, since then it's every couple of months and can last a few nights or a few weeks. We are going through another spell which started on Tuesday.
What I have found is that if she wakes before 5 in the morning, we leave her to cry (after going in no more that 3 times and once we have established nothing is wrong) - and boy, yes, it is hard. She too is strong willed, can bawl for England and makes it sound like she is suffering like hell - it's the worst thing ever. But it is the best way to deal with it imo, if you can put up with the crying as they soon learn that all the bawling in the world won't bring you in so they will eventually give up. Also she is so worn out with crying, eventually sleep is an attractive option once again!
It's only if she wakes after 5 that I have started to take her into our bed - simply because by the time you go through the routine of getting her back off by ignoring (which can take well over an hour sometimes) it's getting on for time to get up anyhow, so it's not worth it and she ends up being really dog tired. I don't like doing it, but as she tends to wake earlier most times, it hopefully won't become too much of a habit.
The other easy(ish) option is to lay on the floor til dc drops off again - my dd loved having her daddy in the room, it was obviously a comfort for her (not so comfortable for him tho, and he's fed up with doing that now!). even with him in the room it could sometimes take her ages to drop off suggesting that like us, sometimes it's a simple case of they just can't get back to sleep easily and lying there in the dark becomes scary and they feel alone .
Good Luck and hope you go back to quality nights sleep soon! x.