There is always a risk with WC (if they were wild caught.) WC usually need immediate treatment. Did you get them tested for parasites or other things right away? Did you get vet treatment for the ones that were ill? Not saying that could have saved them, but it might still save your clown tree frog. I only have 1/8 tree frogs that are willing to tong feed, it's not unusual for them not to, I feed them from a bowl. Also, all new frogs should be in a quarantine enclosure, damp, unprinted paper towel as substrate that are changed every 1-2 days and a water dish for soaking. This way you can monitor their eating and defecating to make sure everything is normal. This way you also would know exactly how many you have left, this does sound like very poor monitoring for a new animal that had to go through the stress of shipping. This is where you should move your remaining frog(s) and toad now (separately of course.) Wild caught species should have fecals sent in for testing, especially if they're having issues, so that they can be treated quickly. If they are carrying any parasites, you will need to break down your enclosures and get them sterilized. Good luck and let us know if you need more help. Did they refund your money for the toad that passed away quickly?