What Causes Stiffness In The Neck With Swollen Lymph Nodes Below The Ear?

I have had chronic stiffness of the neck with limited movement for 4 months now, I also have sore glands along my left jaw line behind and in front of my ear. I have had an mri of my neck and nothing has showed up. I have been on muscle relaxing medication and antibiotics. I am 46 and feel like a very old woman, today my spine is sore. I do not know what else to do my Doctor has rested me for lupus, rheumatoid arthritis but nothing has showed up. I have an under active thyroid from the result of radioactive iodine therapy when I was 23, could this have anything to do with it.