Re: question about a blood disorder.
If your doctor does bloodwork, make sure he runs a complete blood count with platelets. A normal blood count doesn't include the platelets and that's what the trouble is.
Your fatigue could be anemia or ITP. Joint pain and headaches are also part of both, so only a dr. will know by blood tests.
Also, I will tell you that it is possible to have ITP, and not have a normal count, but not have to do any treatments. If this is what you have, let me know, and I can tell you more about my experiences.