To check her throat pick her up and feel along her neck you can also wrap her in a towel if you think looking into her mouth may be a good idea. looks to me she is inside a fenced area, so probably doesn't have access to places where she could have eaten something she shouldn't have. And over heating could be the problem if your having a heat wave. Put her into to tub when she gets out see if she begins to preen, and if she is opening her mouth. I can see her mouth is open but she doesn't look in distress, is she acting like she is in distress? also I have read that spinach isn't good for waterfowl. it blocks the absorption of something I will have to look it up but don't feed them spinach. other greens like kale. Lettuce etc is fine.