If it only started last week and hasn't been a problem previously, then you are more likely to have bronchitis or pneumonia than asthma. Both bronchitis and pneumonia have similar symptoms to asthma. I know this because my kids have asthma and I tend to get bronchitis and/or pneumonia 1-2 times per year.
Go see your doctor. If you've got pneumonia, you'll need an antibiotic. Also, albuterol inhalers can help people with respiratory problems (like bronchitis) other than asthma. I finally asked my Dr. for an inhaler this last year when I had pneumonia real bad.