Oh my god, please don't stress but do call your clinic right now. I spent hours crying and searching online when I saw spotting, but a quick call to my gynac sorted it.
Even though brown spotting is common, you must check with your gynac. Never take a chance with any kind of bleeding or spotting during early pregnancy.
Brown spotting can be normal old blood, but I had severe complications so I always suggest calling your gynac immediately. It is much better to get an ultrasound to be safe.
Please call your doctor right away for advice. I have been through a miscarriage and know how scary any spotting is, so please get it checked to stay safe.
It is often harmless, but don't ignore it to save on clinic fees. It's much better to spend on a quick scan now for peace of mind than to face emergency costs later.
I read that mild brown spotting can sometimes be implantation bleeding. But since it's early pregnancy, maybe just consult your doctor once to be completely sure?