I noticed in the begining of my pg with this one, i would always spot brown a day or after my dh and i had sex. I also had a lot of cramping, mild not too bad. Definately talk to your dr. It can be normal to spot.
I'm not trying to scare you, but the nurse had told me that dark brown to even black blood is ok because it is usually old blood. To make a VERY long story short, it was about 3 weeks after I had missed my period and I tested all negative. I spotted for about 5 days (all brown) and then started bleeding heavily with heavy cramps - worse than a period though. I ended up in the ER because I couldn't wait for my OBGYN to call me back whenever he pleased (I called at 9am and he didnt return my call until 2pm - that's after leaving numerous messages). I ended up finding out that I m/c'd. My point is, you may not be m/c'ing but if you are really worried I would go to the ER. I have health insurance and all I had to pay for all that they did was $100 so I would rather do that than get no answers. It could definitly be normal, but if you are getting really worried I would go to the ER or schedule an appointment with your doctor ASAP. Please don't let my story worry you, I just wanted to let you know my story. So far with this pregnancy I haven't had any bleeding or spotting what so ever - but definitly cramping.