8 month old not sleeping

I don’t really know what’s going on, but my 8 month old is refusing to nap. She used to take 3-4 2hour naps a day and now she won’t nap at all. It’s causing her to be so fussy and I don’t know what’s wrong. She used to go to bed at 9pm and sleep until 9am but now im lucky if she goes to bed before midnight and she is up at 530am on the dot everyday. Should I call her ped?