I had a miscarriage last march, this month i am having a brown spotting for a week but i tested for hpt and it was negative.

Normal: It can be normal to have discharge, brown is typically a sign of old blood. You didn't mention whether or not you had any periods between March and now, June? You may want to see a doctor if you don't want to be pregnant. If you are trying for pregnancy, but haven't had a period for 3 months, that would be another reason to be evaluated by physician. Otherwise, brown spotting is just old blood