What concerns me is that you volunteer at a shelter. I suggested you check out reputable shelters, take your time and research. Poodle crosses are prone to many problems mainly due to the way they are bred. On the 3rd of Aug you asked for advice and on the 6/8 you found your dog.
The over the counter product is not working and you need a vet consult. You are also studying vet nursing so would understand this has gone on long enough.