One of the challenges of home diagnoses is "getting it right". Based on the University of Florida IFAS Extension document (Yangong 2006) on nematode infections in fish, a diagnosis of Camallanus infection seems reasonable. But, like any biologist, my first question is: what species? Is there only one species that you tend to find in freshwater aquaria, or are there many?
According to Yanong, Camallanus requires a secondary host, usually a copepod. I suppose a moderately planted tank with driftwood has lots of room for copepods, even if I can't see them. There are enough hiding spots for them in there. So I'm guessing that control of secondary hosts really isn't an option.