How to get help when you don't know what's wrong

A few weeks ago, I started having a severe pain in my neck and shoulders, and muscle spasms all over when I lie down, or sometimes when I'm sitting at work. I saw a Nurse Practitioner at work. She took me off the [medication] I had been on for over a year. I thought the [medication] had been working quite well, but she replaced it with [medication] and told me my problem was stress. She also prescribed a muscle relaxer. A week later, I felt so bad I went to the ER, where the Doctor also said it is stress, and prescribed a stronger muscle relaxer. Today I am depressed, irritable, and again having muscle spasms and pain. My mental state is back to where it was before I started [medication] over a year ago. I don't know where to turn.

[edited by Anomalia to remove medication names]