I agree entirely with JKRsGirl.
Also 8 year olds see things very differently to adults, so although she may see what you're hiding it may look very different to her. She may be 'feeling' your anxiety but not know why.
If you usually disappear to panic in private she could be feeling a bit insecure or think you're keeping secrets from her and put her own reasons to it.
Personally I think she is far too young to consider meds. Lots of smiles, lots of hugs, fun and involvement are her best medicine.
How old are your other children and are they ok?