Before I would get a new frog, I would toss the old substrate and clean everything else with a bleach and water solution, rinse thoroughly before reusing. How long did you have the frog? Maybe it was sick to begin with.
Where in New England are you? I am in Massachusetts and a director at the New England Herpetological Society, which meets this Sunday at the NEWC in South Weymouth. You are welcome to come by.