Frogs are dying - NEED HELP

[NoviceFrogger]

Hello all,
I am a brand new member and need your help. My son recently showed interest in having frogs as pets when he caught a grey tree frog in our yard. We had the frog for a few weeks and then one morning we found him dead in his cage. I done some research regarding habitats and ultimately invested in a new habitat and bought two green tree frogs from Petco, the habitat consists of the following:

· Exo-Terra natural terrarium mini/tall (12”x12”x18”)
· Exo-Terra Monsoon RS400 rainfall system (using distilled water)
· Zoo-Med 12” terrarium hood
· Zoo-Med Reptisun 5.0 UVB bulb (on/ off 12 hour cycle)
· Exo-Terra combination digital thermo-hygrometer
· Zoo-Med Hydro Ball’s clay substrate base (roughly 1” deep, cleaned weekly)
· Zoo-Med Eco Earth loose coconut fiber top substrate (roughly 2” deep, changed weekly)
· Exo-Terra water dish (using bottled water, changed daily)

We have kept the humidity around 70% and the temperature has been maintained between 65 and 75 degrees F. The frogs were fed 3 small gut loaded crickets each daily, the crickets were fed Flucker’s calcium fortified cricket quencher as well as Flucker’s high-calcium cricket diet. After about 5 weeks one of the frogs had a colorectal prolapse which retracted without human interaction after a few hours. A few hours later we removed the water dish and found a clear jelly like mass roughly the size of a marble, I assume it was eggs but am not sure since it was not deposited in the water. The frog spent the day on the floor of the terrarium with some movement but alert which was far different than sleeping all day long and never being seen on the floor. Long story short, the next morning the frog had passed.

Questions:
1. Is there any reason to be concerned with the health of the other frog?
2. Should I get another companion for the remaining frog?
3. Am I doing anything wrong?
4. After a couple days the coconut fiber is saturated, is that OK? If not how do I correct? Cover the remaining portion of the terrarium top that is not covered by the light hood?

Any help would be greatly appreciated as we are now well invested in having frogs as pets and need to improve our success rate.