Changes in hormones can really make you feel crazy. Many things, including sexual relations can affect the hormones dramatically. Here is a link to some good information about them-
Changing the diet, getting exercise, cleansing and purifying the body, meditating, doing yoga are all things that can help to achieve balance. I would avoid pharmaceutical drugs if at all possible.
When I was having PMS, taking Dr. Lees advice regarding wild yam cream helped me a lot.