2 weeks before expected period had brown discharge lasted two days. Now have bad heartbearn and late period. Neg hpt few days ago. What could it be?

Might be normal. 2 weeks before your period, you ovulated. Around ovulation, related to an abrupt drop in estrogen, you can have some breakthrough bleeding or brownish discharge. With the late period and other pregnancy like symptoms, i would recheck the pregnancy tesst. If you still do not get a period, then it is likely that you ovulated late and your cycle is delayed.