Most physicians like to see written documentation when making a diagnosis for PMDD. Take the time to fill out one of the following forms prior to your next doctor's appointment, this adds credibility in your cyclical symptom claim. Those who advocate for themselves may receive the better medical care. Keeping track for yourself is also a very good idea after diagnosis. Many symptoms can be traced back to specific foods, food additives or food sensitivities.
There are a couple really good symptom trackers out there, here's one from 4 woman.gov, one from American Family Physicians (scroll down) and a very simple form from the cyclediet.com, you can also make your own on any calendar or notebook. The more details you can give to your doctor the more serious they will take you.