I actually asked a question on this site before. I’ve been using Rogaine Foam since September 2007, on the back of my head and the hairline. I was 15 then.
My hair was always somewhat thick, and soft. My hairline had been receding and a dermatologist also said that I had a growing bald spot on the back of my head, based on pictures he took. It worked fine, and in January the dermatologist was actually amazed at the results, especially in the bald spot which was practically eliminated by new, albeit smaller hairs.
Now it’s July 2008, almost 10 months later, and my hair has turned from consistently straight and thick to almost two different hairstyles: the back and sides have all become black, and curly. Really curly. And the rest has become thin and weak and lighter than before. My hairline is straight, but right in the center the hair is especially thin and it looks almost liek a second bald spot.
Whereas when I started, no one could notice the bald spot in the back of my head (although some pointed out a receding hairline), everyone can tell that the hair in the front is thinner than normal.
What’s wrong with my hair?
I would need to examine you to understand the variety of problems you are showing in your hair. I’m sorry, but in your case I simply can’t provide much without seeing the problem in person. It sounds like you haven’t seen your dermatologist since January — I’d setup another appointment for a follow-up.