Had brown discharge 17 days after start of period. No vaginal sex but sexually active. Slight cramps. Occured 1 day then stopped, cycle usually 27 day?

Nothing concerning. Bleeding like this is nothing concerning. Sometimes the lining of the uterus will become unstable and you'll have a little bit of bleeding as a result. It usually goes away. If it starts happening more often, or if it gets heavier, you may need to be evaluated by your GYN.