If your MCAT and GPA are decent (which I think they would be if you are getting interviews), then I think it is time to start asking yourself what is happening during your interviews.
You should set-up mock interviews with someone you know and trust. Try to find someone who has interviewed people in the past and ask them to be brutally honest. How are you answering questions? Run your answers by friends who are socially adept and see what they say about them, because clearly something is happening at your interviews...
What are you wearing? Are you wearing a suit or are you "that" guy who chooses to be different? Is your suit tailored? Are you getting too comfortable and possibly unprofessional with your interviewers? Are you being rude to the office staff? Are your answers to questions scripted?
Also, make sure your answers to interview questions about your application aren't dodging blame for inadequacies, that your reasons for pursuing a DO are in line with your history (examples are always nice), and that your reasons for wanting to go their school are better than "I like the area."
In your situation, you are lucky in that you have close to a month to prep for your next interview. Use that time to get to know yourself and make sure you have tied up any loose ends that you might have danced around at previous interviews.
Anyway, good luck. 😉