Update: The frog is alive and doing well but there were some ups and downs. I thought about euthanizing it but throughout the whole ordeal, the frog was active and non-lethargic.
I started treating the frog with methylene blue and while I noticed some improvement in the beginning, the eye eventually started to bulge out of the socket (see pic) and "burst."
Unfortunately, due to the frog's poor eye sight, it was unable to hunt fruit flies but was able to catch springtails and ff larva. I moved the frog out of a qt bin to an established growout bin that had a booming springtail population. I started feeding the frog mainly springtails and fruit fly larva. I also continued to feed dusted fruit flies just in case it managed to catch one.
This presented some challenges in ensuring the frog was getting enough supplements and I noticed that the frog lost mobility in just the toes in one of its back feet, probably due to lack of supplements.
In order to solve for this, I started including large slices of banana in the feeding station and would sprinkle supplements directly on the banana. The thought process behind this was that if the frog strikes and misses larva or fruit flies located on the banana, the frog would get some supplements.
Even though the frog lost its eye, its regained mobility in its toes, the discoloring around its left eye is going away and it's put on some weight but is still on the skinnier side. Hopefully the frog adapts to having one eye and is eventually able to hunt fruitfly again.
I still have no idea how this happened, but I'm thinking it was an injury that led to an infection and it snowballed from there.