Sis consult your obgyne to check if it is really from the vagina or from the anus. Your obgyne can give you info on what to do next. It happened to me twice (in the vagina) but ruled out the spotting. My OBgyne gave me a uterine relaxant to take up until I will give birth.
Call your OB po agad sis para maagapan kung ano man yan. Di po normal mag bleeding sa trimester mo..