Hi, Kay, and welcome! I have never heard that fibro goes away. It waxes and wanes, sometimes we have flares and other times the pain is quite manageable, but as Joy said, it's always there. So I really don't know what your doctor is talking about. Here is a good link about fibromyalgia from an "expert" at the Mayo Clinic. She alludes to the same facts. It doesn't go away but we can learn how to live with fibro and have a good quality of life.
http://www.mayoclinic.com/health/fibromyalgia/AR00056
Fibro isn't usually a progressive illness so I don't know why you are getting worse. Have you mentioned this to your doctor? Maybe there is something else going on. It's so easy to blame everything on fibro. I discovered this myself a year ago. I was getting worse and since I knew fibro isn't progressive, I headed to a rheumatologist and he ran a lot of tests and discovered something else had cropped up, too. I suppose you could have more pain if you are sitting more and not moving, etc. There are things we need to do to help keep us flexible. That's where the gentle exercises and stretching exercises are helpful. If you sit or lay too much, you will be stiff as a board and have more pain.
Gentle exercises is what is best for fibro. I walk daily or swim. Yoga is another good exercise for us and it really does help with pain and fatigue. So, walk whenever you can. I usually walk about a mile and that takes around 30 minutes....with my dog stopping many times. 
I did start out walking slowly and only could go four houses down but I didn't quit and walked every day and could go further and further. One my body became accustomed to the daily walking it's been pretty easy to do.
My doctor asks the same questions, too, and I've been seeing him for 15 years. I think it's a way to refresh their memories and also to see if you mention anything else. We do tend to forget things when we are at the doctor's office. I make lists of things to tell him or ask him when I go because sometimes my mind is a blank. I also know he has soooo many patients and I certainly can't expect him to remember everything I've told him so I just repeat everything. At least I know he is being throrough. He even runs through the list of prescriptions and supplements I take at every appointment...and I take a lot! This also is good. Some doctors add medications and never take anything away. 
It does sound like your doctor will help you. Your records should speak for themselves. You will be interviewed, too. You also will have to see their doctors so there are several steps to getting SS disability. I hope this helps you.
Since you are new here, please read Fibro 101...the first thread on the forum. There are links to good info about fibro and you will learn a lot there. I've had fibro for decades and am still learning new things.
I'm looking forward to getting to know you better. Don't hesitate to ask questions because we are here to help you. Hope to hear more from you soon.
Sherrine