Sorry to hear about your unsympathetic doctor. They are the worse. I've been there done that all too many times unfortunately.
As for your question about what a dull ear drum means, it generally means that there is there is fluid (usually a very small amount of fluid) in the middle ear. It can mean an infection, but it does not always mean that you have an infection. The ear drum should look like see through Saran Wrap under normal conditions, when your ear drum is dull, it looks more like wax paper or parchment paper and it is difficult to see through. Some doctors describe the ear drum as dull, others choose the word cloudy. It depends on the doctor. You can definitely hear different things when you have a dull ear drum. Buzzing like a bumble bee, some humming like a low melody song but no real rhythm, or even a low beeping/zapping type sound. You can also experience some loss of hearing.
The good news is, it's usually temporary. The bad news is, you usually need to follow up with a doctor if the symptoms do not go away. In your case, it sounds like the doctor isn't interested in following up, which means that she probably noticed no signs of an infection. Since your doctor is not being your biggest ally right now, and should be, you should keep an eye on your system, and see if you notice any signs or symptoms of an ear infection. If you do, you should go back to the doctor, whether it's the same one, or a different one.
Common signs of ear infections related to dull ear drums:
Bloody drainage from the ear
Difficulty sleeping
Fever of 101F or higher
Grumpiness
Irritability
Loss of appetite
Mild ear pain
Severe ear pain
Yellow drainage from the ear
Vomiting
The best thing you can do is "wait it out" unless you see signs of an infection. If you see signs of infection, get back to the doctor. If you experience thick yellow drainage or bloody drainage, go to the emergency room because it can mean that your ear drum has ruptured.
In the mean time, for relief of your symptoms, try Hyland's Ear Ache Drops, they are fantastic. It's all natural, but they truly work. Put 2-3 drops in each ear, along with a half of a cotton ball in each ear. Leave the cotton balls in for at least 20-30 minutes. It takes away the pain almost immediately.
If you are still uncomfortable, you need to get back to the doctor!