*hugs*
Does she get a decent 1-2 hour nap in the day?
My son had "witching hour" (except it went for hourS) from about 1month to when he started sleeping longer naps in the day (so about 4ish months?).
I was googling around to see why he was crying in the evenings and saw one lady say that when she started swaddling her baby he slept longer naps. I figured it was worth a shot so I started swaddling him again (had stopped at about 1 month) and would lie next to him for his day nap (we co sleep so he slept in our bed). I'd nurse him to sleep, then just lie with him knowing he'd wake in 20-30 mins. Feed him back to sleep and after a couple days of that he started sleeping about 1.5 hours for day naps and the witching disappeared.
So if you haven't tried this yet, maybe it's worth a shot.