This isn't a question, at this point, but since google turned up a discussion at this site that helped diagnose my problem (the various doctors I saw were stumped), I figured I would put up a post describing my symptoms and what's wrong with me in hopes of helping others in the same situation.
The post on this site that helped me was this one:
http://www.medhelp.org/forums/RespiratoryDisorders/messages/2320.html
My symptoms and chonology:
It started with a normal, if a bit nasty, cough. About a day into this, I was finding it hard to sleep as a result of the cough. Nyquil and the like helped me sleep some, but not all that much. I had an occasional and slight runny nose and drainage down my throat, but really no symptoms other than the coughing and the sleeplessness.
After a week, I finally went in to see a doctor; I couldn't get an appointment with my primary care physician, so this was someone I hadn't seen before. She said it was probably a virus and would go away within the week; since my biggest problem was failing to sleep due to the coughing, she prescribed something to try to dampen the cough response.
The next morning, I woke to a severe coughing fit, one with a new twist: I couldn't inhale during it. It lasted 20-30 seconds. It felt like my throat was obstructed and not letting me inhale. I also found myself burping up air. When I tried to inhale, I produced a sort of wheezing or scraping sound.
The inability to inhale for so long was a very disturbing experience. My first thought was the medication prescribed, which warned against combining with alcohol, combined with Nyquil was the cause. So I didn't take Nyquil the next night, but it happened again the next morning. So, the next night I took neither... and it happened again in the morning. At this point, I was fairly distressed, and managed to get an appointment with my doctor that afternoon.
A chest x-ray turned up nothing. My doctor decided that the problem was that something (allergies, or perhaps a previously unknown case of asthma) was causing my throat to become inflamed and swollen, and prescribed a steroid inhalant. Two days later, I came down with a fever, and the attacks continued, becoming more common.
The day after that, still with a fever, I went in to see another doctor (this was hitting urgent care, as it was a weekend). This doctor took another chest x-ray and a blood test. The x-ray was again clean. The blood test indicated I probably had a bacterial problem, and also showed an extremely elevated white bloodcell count. He prescribed a codeine-based cough syrup and an antibiotic. The elevated WBC really worried him; he told me to get in touch with my doctor in the morning and arrange for a CAT scan. He also agreed that I should stop taking the steroids (as they suppress the immune response).
The next day, I contacted my doctor, who was less worried by the blood test results and just scheduled me for an appointment a few days in the future. The day after that, I was fed up with this and asked for an appointment with a pulmonary specialist, since I was really distressed by finding myself unable to breathe multiple times a day. In the end, I went in and saw my doctor again. ...but this time I'd seen the post on this site that I referenced before and raised the possibilities that people had come up with. One seemed to be particularly likely -- whooping cough (pertussis). I got another blood test (normal WBC this time -- 1/4 what it'd been two days before), and then another blood test to confirm that my WBC was in fact normal. He also switched my antibiotic regimen to one more effective against whooping cough.
A few days later, my test results came back -- I was positive for whooping cough. Time from beginning of the cough to test results? Three weeks, with, all in all, 5 doctor visits (it was on the fourth where I brough up whooping cough). I don't know how much longer I would have gone undiagnosed if I hadn't found the post here.
It's been a week, and the Department of Health is done quizzing me about who might have been exposed, and all my friends and housemates have gone through a pre-emptive antibiotic regimen. I'm still sick and coughing, and am likely to be for a few more weeks, but I'm finally actually getting better.
The critical bits about diagnosing whooping cough: it starts with normal cold or flu-like symptoms. In more severe cases (like mine), you start getting coughing fits where you struggle to breathe, and this frequently causes the characteristic "whoop"ing noise (which, to my ear, sounds nothing like a whoop, but rather more like a wheezing sound, or like someone who has food cought in their windpipe). By this point, it's entirely possible that the only, or primary, symptoms are the coughing fits.
So, there you go. With any luck, this post will turn up in google when someone similarly afflicted goes looking for information. It definitely helped me to find that post on this site that described symptoms very similar to my own. One poster suggested that it might be whooping cough, and once I raised the idea with my doctor, we were finally on the right track.