I have been with my boyfriend for 4 1/2 years. I have only had sex with him. For the past 2 months I thought I had some type of yeast infection, but today I was diagnosed with "Trich" STD. He told me he's been fatihful. I had the wet smear test 1 year ago, which was negative. Today it was positive. Could this STD have been dormant until now?