I have exactly the same symptoms twice in seven years. I was taking doxycycline for two months and then in an herbal medicine. I also keep having Ayurveda massage, taking Omega 3-6-9 and glucosamine/chondroitin which help me a lot because my main symptom is swelling knees. So far so good.
The tests are not all that accurate, and must be read in light of your symptoms and history. You should ask your MD about taking (more) doxycycline -- and tell him/her whether you stopped taking it before finishing the whole course as prescribed. Best wishes --