My son, who has Asperger's, has been diagnosed by multiple rheumatologists with psoriatic arthritis and fibromyalgia. This thread is old, but the medical info is incorrect, so I wanted to clarify some points. "Benzos" are NOT muscle relaxers. They are anti-anxiety drugs including, but not limited to, Valium and Xanax. Common muscle relaxers which are NOT addictive would be Flexeril or Skelaxin. Soma is also a muscle relaxer, but it's strong and not the first thing the doctor uses. My son's case has been very complicated, and along the way he has taken Valium, Flexeril, and Skelaxin. I hope anyone looking for medical information will not just read posts and believe everything they say but will go to reputable medical sites like mayo to verify the facts.
There is no link between Arthritis and Asperger's, but the doctors have often discussed the uniqueness of my son's case. (They have found no cases previously studied or writings about this combination) Autism spectrum makes pain management more complicated, especially with the sleep issues. It also makes communicating symptoms to doctors difficult.