Sciatic back pain symptoms and conditions

After being on Diovan hct 160/25 for about two years I developed a severe stiffness in my neck, a piercing center chest pain when I coughed and so much muscle/joint pain I could barely get out of bed in the morning. Don't know if it is a result of Diovan, but this is my only med. Finally (after a year) I spent six months undergoing tests and consults with one doctor who finaly gave up. A second doctor diagnosed fibromyalgia and prescribed diclofenac, which somewhat controls the neck stiffness and pain. Now, a year after the fibromyalgia diagnosis I am learning Diovan might be at fault but don't know what to do next. Any suggestions welcome!...