I have had a pretty bad sinus and ear infection for the last couple weeks. I am allergic to many classes of antibiotics. Thus, my doctor prescribed me doxycycline to take even though it makes me nauseas and causes me to sometimes vomit. He gave me doxycycline HCL instead of regular doxycycline and Zofran (an anti-nausea medicine) to stop the nausea and vomiting when I take it. Something surprising happened! After a week of taking the medicines my Fibromyalgia pain lessened a lot. At first I thought it might be the doxycycline, but, after doing some experimenting, I am now pretty sure it is the Zofran. I looked it up and apparently Zofran is sometimes used by some doctors for fibromyagia. Zofran is a serotonin5-HT3 receptor antagonist. I am not sure how that relates to fibromyalgia. I am going to try to convince my doctor to let me keep it permanently unless there is long term side effects. Hopefully, it will last.