New to this Community and have questions

I am 54 years old, and aside from the usual osteoarthritis in my lower back and shoulders, never experienced the sorts of pain and discomfort I've had the last two months. My GP sent me to a rheumatologist last month when I complained about severe bilateral joint pain in my shoulders, wrists and knees and initial blood tests indicated a sed rate of 79 and negative ANA and RA results.

For a couple of weeks, I felt absolutely horrible, tired and full of pain.  At my first appointment with the rheumatologist, he guessed I had adult parvovirus.  I am raising my 5 year old granddaughter and at least one of her classmates was diagnosed with fifths disease (the children's version of parvo).  He sent me out for more specialized bloodwork as well as x-rays of shoulders/knees/wrists.

My x-rays only indicated osteoarthritis in one shoulder and something strange on one tibia near the knee.  I had broken that leg as a teenager so I assumed it was scar tissue appearing on my x-ray, but the rheumy sent me for an MRI just in case.  

However, my bloodwork is a whole 'nother kettle of fish.
ACE 87 (high)
RNP antibodies 4.5 high
ANA Direct: positive abnormal
Aldolase 9.3 High
Parvovirus B19 IgG 5.8 high

Note: My mother has RA.  I have hypothyroidism which I've been treating with synthroid for the last 25 years and I've also been on antianxiety meds for 25 years.

I was relieved at first when he pointed out the positive parvo result, but the doctor was very dismissive of that finding and honed in on the other numbers listed above.  He thinks I have either sarcoid or MCTD.  Sent me for a chest x-ray looking for sarcoid spots and an EMG by a neurologist.  I am currently taking vitamin D (2000/day), Lexapro and Synthroid.  Now the rheumy also has me on prednisone.

The EMG came out normal (whew), but the neurologist said, "OK, your main highway nerves are fine, but we didn't check the side streets."  In other words, the peripheral nerves are what are contributing to my strange tingling, muscle twitches, etc. on my bad days.

I have been feeling better (my sed rate had dropped down to 32 since my first appointment), but the joints continue to give me pain, along with random muscle aches, twinges and very brief earaches.  Clearly, there is something wrong.  Some days are bad, some are good. Today was a wonderful day with minimal discomfort, but I know every day is a crap shoot and tomorrow could be another bad day.

I am scared, depressed, and anxious for all this to be resolved.  Anyone else here ever have this experience of sudden onset of auto-immune symptoms?  Anyone with sarcoid or MCTD care to share their story of diagnosis and how things have played out?

I appreciate any and all input.