Allison, welcome to our little community. Like "OldManEmu" I can tell you that things can change very fast, especially, if your valve area is 0.5 cm2. Last year, I spent a couple weeks in China where we walked vast distances every day. In the evening, I was very tired but things went ok. After returning in early June, I began having some noticeable problems starting with a cold I caught on the trip. By early July, I was short of breath and suffering palpitations which is when my Cardio sent me to have an echo cardiogram and stress test. The test showed that my valve area had changed from 1.25 cm2 to 0.7 cm2 between November, 2008 and July, 2009. A week after the echo cardiogram I began having chest pains for the first time ever. Thirty minutes after I reported the chest pains, my Cardio called to say he had made an appointment for me to see the best surgeon in this area. The next two weeks was the worst time as it was filled with anxiety as I was feeling more ill by the day. The meeting with the surgeon was different that I expected. I still sort of anticipated that he would say that things were really not as bad as they seemed; he did not. Instead, at that first meeting we scheduled the surgery which took place a few weeks later. So, in answer to your question, yes, things can change very fast and, when they do change very fast, it is an indication that the problem needs to be addressed at once.
I think many of us have wondered if this was just our anxieties speaking. You may be psychosomatic about some things, Allison, but If your valve area is 0.5 cm2 you are not psychosomatic about your heart. The good news is that it can be fixed. This experience does change how you think about your body and your life but not all change is bad. This is not a time for procrastinating, when do you meet your surgeon?
Larry