Like ASAP
There are soooo many symptoms involved in pregnancy. Best thing you can do is call your OB or midwife and ask.
I had brown bleeding around 17 weeks and then later in pregnancy too. Brown is less concerning cause it means it’s older blood, the inside vagina is kinda like a bunch of shelves (so says my ob) and sometimes old stored blood can come down. I always was told I had a low lying placenta which is why I was likely spotting brown. Best to go get checked because you’ll want to know the cause but brown is always better than bright red!
I would go to a hospital