Food strike at 18 months?

My daughter has always been a picky eater but for the past couple weeks ever since she turned 18 months she’s barely eating. She doesn’t even want to eat her favorite foods. She has a couple bites here and there and then just drinks milk and water. That’s it. We are trying to feed her what we are eating from our plates, making her favorite foods, and not forcing her or anything. But she pushes everything away and just doesn’t want to eat at all. She’s always been picky but at least she would eat. I don’t know what to do and I’m really concerned. At her 18 month appt, her pediatrician didn’t seem too concerned which is annoying.