I have been told by both Xenopusone and Xenopus express that both beef liver and beef heart can be fed as staple foods as long as you manually remove the fat from either.
If she is eating and you have access to tetracycline *sp in the last post* I would highly recommend you try their method. Allowing the medicine to soak into the food and then offering it to the frog is much more effective than topically or environmentally treating. If you absolutely cannot feed the frog liver/heart you could soak the reptomin sticks in tetracycline, however to my knowledge it is only available in powdered form.