Answer:
Undertreated or mistreated Middle Ear Barotrauma can indeed end in infection of the middle ear. Also it is true that any infection or inflammation of the middle ear or the upper respiratory tract can facilitate or precipitate middle ear barotrauma and, in a vicious circle, further aggravate infection..
Difficult to say what happened in the case you describe, as both mechanisms are equally possible. Given the problems experienced by your student, it may be that an inflammation of the middle ear was already present. Whether it was alerady infected or not, it is impossible for me to say.