needawin, I have the same problem from time to time. Actually I have it at the moment. The doctor told me to use Polytar, in a white bottle. Wash your hair in this three times a week at first. It shuld tell you on the bottle. Just one thing it smells. x
At bad times and if not allergic, almond oil is good. As this is greasy though, for day-to-day, I use Vosene Sensitive but have found the biggest trick is to rub a good conditioner into the scalp after each wash. If I run out of conditioner and just shampoo - I certainly know about it! X