DD has never been a very good napper - she rarely goes down without a fight (unless in car or pushchair) and often will only sleep for 30 minutes.
But the last week or so every time I put her down (even if she's rubbing her eyes and grizzling with tiredness) she goes MENTAL. Climbs down her cot, stands up and wails and could go on apparently forever.
Her pattern is pretty rubbish but she usually naps about 3 hours after waking and again about 3 hours after that. If she's in the car she goes to sleep without a murmur.
She's also been terrible at night the last 3 nights - waking virtually every hour. I'd think overtiredness but there's been plenty of days when she's done 2 x 30 min naps all day and slept fine so I think possibly that's teething.
Try Calprofen and see if that helps. If it does, it's teething. Molars and canines are fantastically painful. DS would only sleep longer than 30 min at a stretch if medicated. If it's not teething, it could be development. Is she about to start walking? pointing? saying a first word? Or is she going through separation anxiety (classic age for it TBH)?
My 19 week old has been doing same for 3 weeks now similarly she only ever naps for around 30 mins and she will gave 4 of these each day. I don't have any advice sorry but they do say misery loves company! Only thing I have found is if I catch her during the window of opportunity during the day it is a lot easier to get her down for naps with minimal screams although they do only last 30 mins.