Im 5wks pregnant have had slight cramps here and there for about 2wks 2day i noticed a lil brown blood on my underwear what's going on?

May be fine: It is common for women to have a little bleeding around the time the embryo is growing into the wall of the uterus, called implantation bleeding. This can occur around the time of the missed period. Some cramping in the first trimester is also common. However bleeding and cramping that are getting worse can sometimes occur with a possible miscarriage. Check with your doctor.