For the past 3 or 4 weeks my daughter who is 16 months has been extremely clingy (only clingy to me), not wanting to eat…

For the past 3 or 4 weeks my daughter who is 16 months has been extremely clingy (only clingy to me), not wanting to eat much, and she has been waking up multiple times a night and not wanting to take a nap during the day when she has been sleeping through the night for over a year and normally takes at least one nap a day. When she is being fussy we make sure she isn't hungry, needs a diaper change, uncomfortable, or wanting to play with different toys. Even sometimes when I'm holding her she gets fussy. What could be wrong with my sweet little girl?