Each front leg exhibits a single ear below the knee with two eardrums (also known as tympanic membranes), which are backed by a narrow cylindrical tube (the acoustic trachea) running along the leg internally and opening out on the side of the insect's body. (sciencedaily.com)
However, if there was lots of pus and no eardrum (which I would infer from the statement that there was a «middle ear infection with pus»), the middle ear (tympanic bulla) will need to have any debris removed from it. (yourpetsbestfriend.com)
However, anuran species have lost tympanic middle ears many times, despite anurans» use of... Proceedings Royal Society (anfibiosecuador.ec)