Naomisky,
I have not had your exact experience but I have had my fair share of rejections and I know it can be even more of a bummer when you feel like you did great at the interview, so I am sorry you got bad news.
I have heard criticism that post-rejection feedback from UW tends to be vague and open-ended, so when I didn't get in last year I created a new thread on SDN in the "what are my chances?" section, where I listed the important points of my app and asked where I could be improve my chances. I was very pleasantly surprised at the willingness of SDNers to offer advice and help, I got several responses within days, and I found that particularly useful in determining how to strengthen my case for reapplication.
Not knowing all the details of your case, it is difficult to make accurate suggestions, but I have some general ideas. UWSOM is a heavily research-oriented school, and I am given the impression that having some research experience on your app goes a long way toward improving your chances. You noted concern that it might have been over something you said in the interview, I find mock interviews very helpful in addressing points in my speech that may have been unflattering; and having someone who does not know you well (ie a professor or some member of your schools Health Science Committee) or is otherwise able to be objective and critical do the mock interview, as some mock interviewers are averse to pointing out negatives.
I received 30 rejections last year, and I can tell you that having someone who believes in you no matter what means everything, don't take that for granted, and don't get discouraged. Reapplying shows that you have resilience, tenacity, and unequivocally reasserts your passion to get into medical school.
