Severe menstrual cramps with little mucusy bloody brown discharge! What does that mean? I don't feel breast tenderness or nausea to suggest pregnancy.

The brown discharge. Is usually, older deoxygenated blood being cleaned from the uterus. If this is your period then you are not pregnant. However, since it doesn't sound like it is characteristic for your normal period - taking a pregnancy test can provide you with definitive information. Take care.