Suggest Ways To Rule Out PANDAS In A Person With Down Syndrome

Question: Our 27 year old daughter with Down Syndrome suddenly went into a state of severe regression and altered mental state four months ago at which time she showed/s signs of dementia, psychosis, rapid weight loss and severe insomnia. MRI and CT brain scan showed normal other than Calcification of the XXXXXXX Ganglia. Blood work has found Hypothyroid(treating with NatureThroid), low Red Blood Count with elevated MCV, MCH levels. She has been diagnosed years ago as being a Strep Carrier. She was exposed to a strep infection end of January and one week later ran a fever for over 2 weeks and had a sinus infection, was treated with antibiotics. An Integrative Dr wanted her blood work tested for Strep A and so in the month of May blood work for an ASO titer flagged high at 362. ASO titer was again tested in XXXXXXX with range of 413 and again in August at 517. She had a EEG after 2 fainting spells and her Neurologist indicated that Strep can go to the Brain.

It has been suggested that she may be suffering with PANDAS. We want to get to the bottom of her illness not just guess.
XXXXXXX is also Gluten intolerant and is on a Gluten Free diet. She will often go into severe crying spells within a few minutes of eating. However these crying spells and talking to herself will also happen continually throughout her day making it very difficult for her to function outside her home. Even with family members she is very much disconnected and in a state of depression....HELP??? We do not want to just put her on Psychosis medication. We want to know what has caused her to change so rapidly and significantly. She is very ill!
She has undergone multiple tests but we are not getting answers or resolve. XXXXXXX had a Pace Maker dual chamber implant 5 years ago due to Syncope. She uses a CPAP however recently infrequent in that she is in a pattern over the last 2 and a half months of being awake 36 hours straight. She will only sleep every other night.