The following are signs of toad toxicity. Only some of them may be present.
Mouth irritation with foamy salivation after initially licking or biting toad.
Your dog has some of these signs, so it is possible, but it is also possible that there is something else going on that is making him sick.
At the time it happens, we recommend rinsing the mouth out thoroughly , then get them to a vet as it can be deadly within minutes. At this point, it is likely it wont be deadly to your dog if this is what it is, since he has made it so far.
The toxin can effect the heart and cause it to beat irregularly. So we would still recommend he gets to a vet so they can check the heart and give medicine if needed. If it does not seem like this, then they can try to determine what else is going on.
If there is no way to get to a vet, continue to do what you are doing by paying good attention to him, feeding him and making sure he drinks water. I hope this answers your questions to help your pet. If you have others, please let me know.
Feedback is always greatly appreciated.