Meirad, when you say pops and crackles I'm going to assume you mean that there is a sound kinda like fireworks/firecrackers going off or your ear physically pops like an elevation change?
I'm going to assume the first for now. I don't personally get the pops and crackles but I have heard of a few people with menieres that experience this. The pops and crackles may precede and attack so keep track of when they occur versus hearing fluctuations.
Unfortunately with a 4 hour long vertigo attack, that keeps straight up menieres in play. All of my few vertigo episodes have lasted less than a minute.
Another sign of either DEH or menieres is a reverse slope hearing loss where your high frequency hearing is better than your low frequency hearing although this is not a requirement.
PS. ENTs specialize in middle ear (as well as nose and throat) and may not be able to diagnose this. Definitely still go and present your symptoms and get a hearing test. If they aren't able to help, I would find your local nuerotologist/otologist as they focus on the inner ear or even ask the ENT for a referral. I went through 4 ENTs before I was referred to a nuerotologist that had answers. YMMV.