My 7 year old daughter had fifths disease. It lasted approximately 2 months (the entire summer vacation basically). The hives were unbelievable! Do you also have that? I am told that with adults there is a tremendous amount of joint pain unlike with children) and the disease will last anywhere from 3-6 months. I would go see the doctor for more tests if i were you...since it is now over the 6 month mark. Just my opinion. Hope you are feeling better soon! Good luck.