You should be alwright as long as your bleeding doeznt get any worse like period blood red and cramps and clots but see your doctor asap
I think vitamins only change the color of your pre. Brown blood is old blood, you don't need to worry about it. If it's pink or red blood then it's fresh and you should call your Dr.
I urge you to get checked out lots will say that brown spotting is fine its just old blood but my first pregnancy I had brown spotting and was told it's just old blood I ended up miscarring so I urge you to find out