Hi Kat,
It's normal to be scared. Like Becsbuddy, I have an auto-immune disease that left lesions in my brain - talk about scary! One thing that helped me tremendously was meditation. I can't explain it but it was like a miracle when I was going through my treatments and procedures (9 MRIs, lumbar puncture, etc.). I use the Headspace app on my phone and it was so comforting when I was in between the times of trying to figure everything out. I hope your PA is helpful. Keep in mind that auto-immune diseases affect more than one system in your body. In my case, things were constantly changing as my body adapted to the treatments (I was on high doses of Pred for 6 months and then Rituxan). To be honest, my acute phase was 13 months ago and my body is still changing even now (luckily, getting stronger and healthier). Hang in there!