The test is useless within the first few weeks of being bitten because it takes a few weeks for the body to generate enough antibodies to be detectable on the tests. But testing the tick is a good way to find out if there is even a possibility of her getting Lyme from this bite. You might also consider giving her a homeopathic remedy called Ledum ~ it is for insect & spider bites, and is also known to help in acute cases of Lyme (i.e., newly infected cases)...with the Ledum, two pellets dissolved under the tongue is the usual dose, and I'd do this daily for a week. If no symptoms show up in that time, discontinue the Ledum. Homeopathy has no side-effects, and there should be no interaction with Doxy (or other antibiotics). I also think she should take the Doxy.
I hope this helps...take care,
Chronic Lyme Disease, Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, etc.; G-Tube; TPN via PICC (trying again to wean off the TPN).
Meds: IV Cipro, Heparin (to flush PICC line), Singulair, Claritin, Domperidone, Colloidal Silver, probiotics, digestive enzymes, Milk Thistle, Magnesium, homeopathy.