I am 29 years old, 118 lbs, 5 2, and have 2 kids ages 10 and 8. 8 years ago at the age of 21, I had my tubes clamped with hulka clips. I have had semi- regular cycles until this last month. The last week of July was my last cycle and it lasted 2 days, which is normal for me. But, then the last week of August I had some brown sticky discharge with very light amounts of blood in it. So light, I used panty liners instead of tampons. This has never happened to me before. This lasted 8 days. I have had some light cramping nausea and headaches, but no sore breasts or anything else. I have taken a home pregnancy test last week and it was negative. Any ideas as to what could be causing this?