I'm not a doctor but I have had friends that had a similar problem as yours and ended up having a NORMAL pregnancy and healthy baby. I'm pretty sure that you will be fine unless you start cramping or start having a lot or red colored blood. When i was pregnant with my 2 year old i was a fanatic on reading everything out there about pregnancy, so I've read just about everything! Also you said you're around 4 weeks pregnant which would mean it would normally be time for you to have your period, and the first couple of months of my own pregnancy I would have brownish/pinkis discharge around the time that I was supposed to be on my menstrual cycle every month.