I second DeterminedMom regarding the steroids.
I spoke with many LLMD's in the past and they all said "never use steroids unless it's to save your life". They said that 'if you have an active infection and take steroids the steroids allow the bacteria to take over and prevent the body from fighting.'
If you're considering the study @ NIH, call and talk with Dr. G regarding any medications that might exclude your DS. He can also email you the 39 page protocol. I carry a copy with me to all doctors appts. He has been very patient and helpful in talking with any of the pediatricians that I have asked him to call.
I am taking my DS to the NIH in 2 weeks (sooner than I could get into see some neurologists and/or pediatricians!) and I just started conversation with them the end of March. They were going to get us on the 16th, but we couldn't go. (My DS developed sudden-onset OCD Feb 10th, and it exploded on March 23rd.) Luckily for us the neurologist in SW Florida that I was able to get a cancellation appointment with, was knowledgable about PANDAS and the study!
Good luck to you and your DS. Hugs.