It's so frustrating when they suddenly change when something was working so well, isn't it.

Have you tried putting her in her pram to nap? My dd has only slept well during the day in her pram for months. If I put her in her cot it's usually 30 mins max, whereas she sleeps for up to 2 1/4 hours on a good day in her pram. I don't wheel it around, just feed/rock in arms to sleep and then pop her in the pram in the hall at home unless I need to go out. She sleeps fine in her cot for the first few hours at night (and sometimes all night), and then into our bed, where she self settles without a problem.

Over the months, when babies in my mums & bubs group have had daytime sleep issues they've tried sleeping them in their prams and it often works. One was having problems in the evening and for a few weeks she put her DD in her pram until she went to bed, when they would then co-sleep - it gave them their evenings back where previously they'd been holding their DD and taking turns to eat etc.