I'm a bit confused.
Her crop empties out, but then you say her crop doesn't empty overnight. Which is it - emptying out or not?
Are you taking out the food/water at night and is she sleeping in the dark all night long?
Get some more photos of her poop.
You can stop the corid if you wish. You were given the dosing for your quart waterer which is 1/2 teaspoon of Corid per quart of water - you put in a "two or so teaspoons"? Do you have measuring spoons?
Just stop the corid.
Miconazole is given 2 times a day for 7 days. Re-check the crop again in the morning.
Your chick may be failure to thrive, hard to know. I think you are doing all you can for her.
Corid is not an antibiotic, it's a Coccidiostat.
It's a Thiamine analogue and block the thiamine transporter of Coccidia (which is a protozoa). This "mimicking" of the thiamine helps inhibit Coccidia from getting the "nutrients" it needs and "starves" it, so the numbers are reduced so the bird can build resistance. Corid does not kill good or bad bacteria, it simply helps prohibit Coccida from absorbing Thiamine.