I do have achy skin. Most of the time it feels like I was rubbed with sandpaper but sometimes just achy. Never a rash or visible mark, just pain. I also have randomly painful joints and muscles. I have not been diagnosed but I gave up seeing doctors a few years ago. They weren't helping me and I got tired of it, and a little broke after all the dr. bills that seemed to be for nothing. My mother has fibro and she has the same symptoms I do, hers are just more severe. I started excersizing and eating healthy which has made an incredible difference! Just getting myself overall healthy has made a difference. However, for my mom, she can't excersize much because her fibro and chronic fatigue is real bad. I have Thoracic outlet syndrome which causes a lot of back pain.
Go to your doctor and request a referral to a rheumatologist. Make sure you have a complete list of all your symptoms. My legs broke out in open infections but healed before i finally went to the doctor. If I had taken pictures they could have seen what was going on so if you have any visible symptoms it is important to document them and take pictures. Also, when I saw a rheumatologist, it was difficult for me to explain everything (what kind of pain, how long it lasted, how severe, how often it happens, etc.) I got a small diary to fit in my purse so whenever I had pain of any sort, i wrote down as much info as I could about it.
Good luck and I hope this helps