Sorry to hear about your toad. My first suggestion to you would be to quarantine your toad away from your healthy one. A simple setup consisting of a secure small plastic critter cage, filled with paper towel, a small plant for cover and a small, low filled water dish will suffice. This will allow you to better observe him/her and be able to feed it separately and see if it is actually eating or not. Not being able to see the toad or observe it, it will be hard to say exactly what is wrong. Are you able to take a picture of it, especially the eye? My second question is the feeding: are you dusting the crickets at least twice a week with a calcium and vitamin supplement (once a week for each)? As well, what kind of setup do you have your toads in? Hopefully we will be able to help you and your toad.