I apologize if you've posted your tank conditions before, but would you mind posting some more details? Size of the aquarium, filtration system, decor, any tank mates, etc.
What are you feeding her? I don't recommend pellets for an African dwarf frog, as many won't even touch them. I would instead suggest trying frozen foods (thawed out first) such as bloodworms, brine shrimp, mysis shrimp, and small chunks of krill. If they're available to you, live foods are even better (bloodworms, brine shrimp, pinhead crickets, and blackworms are some common ones).
If she's not finding food, try using tweezers to wave or drop it near her. I've had to do this for a few frogs, although all but one eventually got better at finding it.
That pH is a bit concerning, but a stable pH is better than one that fluctates...in other words, don't use any of the products designed to lower it. However, you could try to lower it naturally by adding some driftwood to your tank
. She'll love hiding in it, too.
Do you have a picture of the reddish skin and spot? Are her eyes cloudy at all?
It sounds like a fungus and I would do daily water changes and maybe try a diluted medication (I've been told that ones including Malachite green are good, but have never had to treat an African dwarf frog for anything). Unfortunately, there aren't really medications available for dwarf frogs, and not much is known about treating them.