The asthma diagnosis came after the 13th birthday and was disclosed on all the initial medical forms. In order to get the waiver, we had to provide additional medical records related to the asthma, as well as two separate letters from the physician answering specific questions as to the intensity, severity, and frequency of any asthma issues. Asthma never interfered with sports or other activities, but did have to use an inhaler in certain circumstances. However, the inhaler and any other medications hadn't been used for several years prior to the USNA medical. I believe that it was the asthma diagnosis after the age of 13 and the use of an inhaler that is what influenced the need for the methacholine challenge test. I know that this is stressful for you and that there is a lot on the line, but the best thing that you can do is not stress out about this test. I know this is easier said than done, but there is no way to prepare ahead of time so that you can "pass". You will have a good idea right there and then how you did. If you don't have any issues with your asthma right now and it doesn't impact your activities, then you will be fine.
Good Luck! Please report back with an update, so I know how things turned out. You got this!