Hi,
My 8 year old daughter had PANDAS Anorexia Nervosa and was hospitalized for a week several months ago due to malnutrition (she had gone from 47 pounds to 42 pounds in a matter 2 weeks). (FYI her tics started late, after 2mo, but every PANDAS kid is different.)
I would get *throat cultures* on everyone in the household (including your daughter and siblings). Insist on the 48 hour culture if the rapid tests are negative. Our daughter cultured postive. She had had a fever (which we realized later was strep since other kids from her class were sick with strep at that time) 2 months previously and that's when the behavior changes and restrictive eating started. Her younger sister (no symptoms...a carrier we assume) also was also postive for strep. (Note: there could also be strep hiding out elsewhere in the body so a neg. throat culture is not the end all.) Interestingly, by the time my daughter was hosptalized and strep titers were drawn they were *not* elevated...despite the positive cultures (but that's another discussion.)
SSRI's were somewhat helpful with the depression/eating but the real cure came after several months when we finally put her on Azithromycin. By day 5 she was yelling at us less, a few days after that she decided she wanted to get better, then she started eating 3 meals a day. After4 weeks of Azithromycin she was pretty much back to normal, eating like a regular kid with no more questions about "will this make my stomach grow?, does this have sugar in it? will this make me fat?", tics were almost entirely gone. She is still on Azithromycin...we have no plans to take her off in the near future after 5 months of OCD, insane behavior, depression, and anorexia nervosa. Note: after diagnosis she and her sister were on several antibiotics once we found out about the strep and Azthromycin is the one that "cured" my older daughter and cleared the younger one of the carrier state.
If your daughter is severely underweight re-feeding will be critical as well. A malnourished brain cannot function or heal well. If she is severely underweight she is immunocompromised.
Suprisingly, we also discovered Advil (Ibuprofen) was helpful with my daughter's PANDAS AN symptoms. We discovered this before Azithromycin and continued the Advil until recently. (I don't know if I would rec. Advil for your daughter if she is complaining of stomach pain but something others may find helpful.) She is still on a low dose of Prozac (a little added insurance to keep the AN away), the Azithromycin, a multi-vitamin and probiotic.
If your daughter (or siblings) have strep I would also change toothbrushes a few days into a the course of antibiotics. Give each kids their own toothpaste as well. This will help prevent reinfection.
Good luck. I know Anorexia Nervosa is a huge nightmare and am so relieved that it is over (knock on wood) for me. If your daughter does turn out to have PANDAS AN keep in mind that you are facing an uphill battle since most pediatricians, dieticians, ED specialists do not understand or even *believe* in PANDAS.