Can 3 days only of Propecia 1 mg cause permanent damage to me?

The symptoms you describe may also occur with intestinal upset, irritable bowel, food allergy, or constipation and the associated psychologic stress.  The sexual side effects from Propecia are quite rare, so I would not jump to the conclusion your symptoms are from Propecia unless these symptoms persist beyond one week or worsen. If symptoms do persist or worsen, then I would consider seeing either your primary care physician or a urologist.   

Long term side effects would be quite unusual with Propecia.  If your discomfort does not improve over the next few days, or worsens, you should see a physician, preferably a Urologist.