What Causes Pain Due To Myalgia And Myositis With Knots In Neck And Shoulders?

i have had unspecified myalgia and myositis with knots in my muscles they are in my neck my shoulders and in my back near my shoulder blade very painfull i have to have them rubbed out all the time. i have had this for 5 years now it has gotten to the point i had to quit my job a year ago i filed for disabitily i cant lift anything without pain