Hi tiffanysb, and welcome to the boards.
Your note about being under an abnormal amount of stress is important, as stress can indeed impact your menstrual cycle
and even spotting between periods. Brown discharge may just be normal discharge with some blood in it, which isn't necessarily something to worry about.
If you used the test correctly according to the instructions (more on pregnancy tests
), then you're not pregnant, and this discharge is likely related to your normal cycle in some way. Or, as you said, there could have been a small vaginal tear. Tears can be avoided with plenty of lubrication