Hi I'm 18 years old my last period was aug.26.2007 and in September I didn't get a period but October.10.2007 I started to have brownish discharge sort of like a like period and it lasted only a week (7 days) from October.10-october.17 I don't know what can it be a bought a pregnancy test it came out negative I took it on the 14th of October 2007 could it be that I'm too early in pregnancy I mean I don't think it's in infection I have no symptoms of one or can it be something else please reply to me as soon as possible I'm worried?

You are most likely just suffering from irregular periods. Brown discharge is just old blood. It is most likely due to a very light flow. I used to have the same occurrences... my doctor said they "counted" as periods.

Are you having unprotected sex?
If so, then I would call your doctor and request a blood pregnancy test.

But again, I would venture to say it was just a light period.
I would wait and see what next month brings.