Sorry in advance for the novel.
First of all, take a deep breath and don’t panic!
I was diagnosed with both lupus and fibromyalgia 5 days before my 40th birthday. (Happy Birthday! 
). I am now 68.
Before the diagnosis, I had about 6 months of feeling exhausted all the time. I was in the military, fit and a runner, so not being able to walk up a flight of stairs without pausing was really terrifying. I had muscle weakness and stiffness, pain in joints, odd rashes that came and went and muscle twitching in random parts of my body all night long, thus not getting any sleep.
I was put on hydroxychloroquine for the lupus and cyclobenzaprine (Flexeril) for the fibromyalgia symptoms. It took a couple of months to start feeling normal again.
During this time, I continued to mostly get on my mare. I would ride a little then take walking breaks as needed. One of the worst parts for riding, besides the exhaustion, was that my hands would cramp up after about 5 minutes. I would have to walk and massage my hands before I could hold the reins again.
There were definitely days, mostly during the first year after diagnosis and during warm weather, when I would need to have a trusted friend exercise my mare while I sat and watched. It was very frustrating. But within that first year, I went into remission and pretty much resumed all of my own riding and training, up to taking clinics with a couple of well-known dressage clinicians. Before I lost my mare at 13, I was schooling third, with bits of fourth. I had started her off the track myself, so I don’t feel that the lupus and fibromyalgia prevented me from bringing her along, it just took longer to accomplish.
Through the years, I have had the occasional flare-ups. These mostly occur in hot weather or when I consistently don’t get enough sleep or eat well. I am also very affected by environmental factors, such as fumes of any kind. (They had to re-tar the roof of a building where I worked, and I was really sick for about 10 days with the worst flare I ever had).
The sun is also a big enemy with lupus. Before I retired, I rode after work in the evening, Even on days off, I did not hit the barn until after 5 and always slathered on sunscreen.
I had my gelding for decades and rarely didn’t feel up to riding. If I had a flare, I would lunge him or walk on the trails. I was always prescribed prednisone for the flares but hated the side effects so much that I have refused to take it for years. If I feel a flare coming, which is pretty rare now, I just take it easy for 2-3 days and can pretty much bounce right back to normal activities.
There have been so many improvements in treatment over the years that the VAST majority of lupus patients can live a normal lifespan with the occasional inconvenience of flares.
Kind of funny story: Before I received the official diagnosis, I had started reading up on lupus (at the library, this was before the WWW). All the medical reference books were saying that lupus patients had a 50% chance of living 5 years. So I was thinking, well I can fit a lot of living into 5 years. I was also making plans and asked my best friend to take care of my horse and 2 cats.
The day I walked in and got the official diagnosis, the doctor said, well, you have lupus. And I said, very calmly, so I have a 50% chance of having 5 more years. He looked at me strangely and asked why I thought that. I told him about my research. He explained that the reference books had to have been out-dated, because with new medications and close tracking of the disease, that prognosis no longer existed.
You don’t have a diagnosis yet. Even if you get one, it is NOT the end of riding and living your best life. Irritating and inconvenient at times, but very doable.
Why are they saying that they need 2 months to give you a diagnosis? Have they done an anti-double stranded DNA test? I believe that’s still the gold standard for diagnosis and typing of lupus. Getting results for that shouldn’t take more than 2-3 days.
Since there is no one test that diagnoses fibro, they should be able to give that diagnosis once they’ve ruled out other things.
Sending you hugs and prayers in this very difficult time of waiting. If you have questions or just need to talk, please don’t hesitate to contact me here or via DM. 
Pam
