It was in Malawi (apparently the 2nd cheapest place in the world to do a dive course- if anyone knows what the cheapest place is, please tell me. It's been bothering me for ages.). I had no idea I couldn't do a dive course with asthma so obviously I hadn't really looked into it too much. They didn't have any sorts of doctor facilities there, so they were point blank refusing to take me on, which is fair enough- my asthma's not bad, but I'd certainly get a proper consultation with a dive-doctor first in the future before attempting it
maybe I'll do that one day, and go on a course when i'm richer!
I ran into a similar problem in Jamaica - didn't have a letter of health but because I was 46 (over that 45 year old limit for that dive facility), I spent a full day calling home to get a letter of health faxed to the facility by the next morning's dive time. I missed 2 dives but learned a valuable lesson. Never leave home without a letter of health.
Another valuable lesson I have learned - never trust the "dive doctor" a facility recommends. I could have paid an extra $75USD to have the "recommended dive doctor" approve my sign off sheet without a medical exam. It may be just me (us), but I take my diving seriously enough that I don't want to put my dive buddy (beerman) at risk. I chose to wait until my (real) letter of health was faxed down to the resort. (I think beerman would be upset if I didn't surface at the same time he did. He's funny that way.)
I can't tell you the cheapest place to become certified, but I can say use your own doctor for the letter of health. S/he knows your history and can vouch for your physical abilities. They also know the medications you are using to control your asthma.
I haven't forgotten about you H!!! Really!!!