Hello; I began a week or so ago having thick stringy discharge, first clear and now brown, along with cramps and back pain. What could it be?

Brown = Blood. A normal period lasts seven days or less. If you're having old brown blood before or after your period, then that's not normal. Occasionally we have some spotting during ovulation. If these symptoms persist, i generally recommend seeing a doctor for an examination and possibly an ultrasound to check on this type of problem.