Well im strongly suggesting to change your vet asap. place your frog in hospital set up and stop using amikacin. Both things gotta be done asap. What form of amikacin are you using? Where are you applying topically? Do you know dosage?

Next - find vet who knows what s/he is doing. While looking get flamazin (silver sulfadiazine) cream, use that for the wound (if it is still there).
i dont see lumps, except the opened one, depending on a location and feel of them it might be lots of different things. Can you describe more? Im assuming hystopathology was never done? Do you know what did came out when vet open the lump?