Good Sleeper Gone Bad

I'm having trouble with my 23 month old sleeping all night. For the past three weeks she wakes up numerous times which she never use to.
It's waking and screaming and asks to a bottle but we just give her water and she throws it across the room.
We've tried numerous things to try and get her to sleep like not having a day nap, giving her back a dummy (my husband's idea) she didn't want it and homeopathic remedies.
I'm so tired as I have a six month old who gets up at night just for a nappy change then goes back to sleep. I'm out of ideas I just want my good sleeper back.