That is a criticism I had of Dr. Cahill. His test can be good if it finds something but if not he doesn't do much else. He runs some general blood work and gave me a serology for amoeba once and that's it.
He also left a message on my phone after a visit with him this year that since his test and serology found nothing he said he sees no evidence of infection and to give it time, so he didn't even offer extra help to look more into it.
It could be worth seeing him once if the few hundred dollars and trip isn't a big deal but his chance of finding anything depends on if his test picks something up which is hit or miss.