fish_bowl once bubbled...
In our course our instructor told us not to use decongestant but I think he was refering to when you are sick. Which of course I would not dive if I was sick but I think I will try this if this problem persists. Fish
No, he meant anytime. There's a danger it may lose it effectiveness at depth (some drugs are adversly affected by increased pressure, higher blood gas levels of nitrogen and oxygen, etc, in some cases having stronger effects, in some cases less). In such a situation you could suffer a reverse squeeze and rupture an eardrum on ascent (and ascend you must). Be very very careful here.
Can you better describe your problems afterwards? Did you discuss with your instructor? If you get behind the curve on equalizing, you will suffer minor barotrauma (big word and I'm NOT a doctor, but have consulted one as my ears are slow to equalize) which repeated over time is not good. In my case I need to descend very slowly for the first 10 to 15 feet (area of a fastest rate of change), equalizing almost every foot and preferably in a feet down, as if standing, orientation. Once past the 15 foot point, changing to horiz, it becomes much easier. The better news, is the more I dove, the easier it becomes. A couple of other tips, lots and lots of water (which will help thin any mucus) and try avoiding milk on the day you're diving and maybe the day before, in many people, milk (and milk products) will increase mucus production.
You could also ask your family doc for a referall to an Ears, Nose and Throat specialist.
The "swimmers ear" of which was spoke is the outer ear canal, and is an infection caused my bacteria present in the water your diving in remaining in the outer ear canal. A drop of peroxide in each ear after diving is an excellent preventative, but don't overdue it. Special drops to prevent swimmers ear are available at most pharmacies. Many help get rid of that nagging feeling of water still being in your ear by breaking it's surface tension and allowing it to drain.