It very well could be asthma. A lot of people often talk about asthma with children and not so much with adults, but of course, anyone can develop asthma, regardless of their age. I know a lady who was diagnosed with asthma in her seventies, in fact. But anyway, I really think you should visit your doctor before your trip, and tell him/her about your symptoms and the possibility of asthma and such. There's definitely something going on, and hopefully you'll be able to grasp it before going to Alaska, because Alaska's quite cold, and sometimes cold air can be bad for asthma. Well, have fun on your trip, and good luck, I hope you start feeling better soon. Hope I helped!