Swollen or enlarged lymph nodes in the armpit, groin and neck usually point towards bartonella. Bartonella can sometimes be contracted from cat bites or scratches and even from flea bites. Of course, this cat would have to be infected and they usually show no signs of infection. The other transmission route of bartonella would be as a co-infection from a tick bite. Often present with borrelia(lyme), babesia, ehrlichia and a number of other pathogens or parasites.
Lyme and babesia have been rumored to cause lymph abnormalities but bartonella is more likely the culprit. I think sometimes babesia and lyme tend to affect the glands, most commonly the parotid saliva gland in the neck near the jaw.
Lymph nodes can also become abormal from other infections(viral, cmv virus etc) or even cancer(lymphoma) in some cases.
Sometimes you have to explore and try different antibiotics before you find one that works. Doxycycline does not work for certain infections, for example. But then you end up trying a macrolide or cephalsporin and start to experience a herx or see results. Trial and error in some cases.