being at 5 weeks im sure it would be way to early for the doctor to see anything.... i had brown spotting and i was around 5 weeks . my body was going through a miscarriage but slowly... my cervix was closed and everything intill about two weeks later. that brown blood followed by red... i mean stay onbed rest... hopefully thts not the casrcase for u.. brown spotting can be an indicating of many things.. good luck and take care of urself.
Most likely it is what they call implantation (when the egg attaches to the uterus). It is normal to have a light spotting and the light brown it turned is it is just drying up and slowing down.
Sometimes it's completely normal. I had some brown discharge around 15 weeks last time and my doctor told me it was likely because we had intercourse the day before. Your cervix is sensitive at this point. Everything is changing. Always talk to your doctor if you're bleeding any colour of blood, just to be safe.