I'd doesn't have to be an infection. We all have small amounts of candida. Everyone. Some of us have different strains that are more virulent. I just happen to have a lower immunity in my lymphatic system to keep in check. My circumstances are very unique. 37 years old, very good shape, not over weight, eat well and exercise daily. I'm actually a personal trainer. But like all people I enjoy a drink here and there and eating out from time to time. These things are what tip the balance in favor of the yeast getting out of control. My body has little ability to fight back. For reference I was completely free of it last November. But when i went of supplements and probiotics all it took was a basketball game and 3 beers and it slowly crept back to full blown attack mode over the last 5 weeks. That game was April 2nd. Like most of us I'm super obsessive when it comes to this. It's taken me years to figure this out.

Also for reference mouth swabs are false negatives 25-45 percent of the time with candida.