Why am I spotting

So I went to the ER last Saturday for a wipe of red blood spotting. I freaked out, no pain... They ran a bunch of tests and the baby is fine and there was no source of why I bleed. I was sent home knowing everything was fine. Today, almost a week later... I wake up to the exact same thing. One smear of red blood only once- no pain. I didnt call anyone or went to the ER- I have an appointment this upcoming Wednesday. I cant even afford my bloodwork from my prenatal visit (basic BL was $400 out of pocket pay) and the ER visit im sure will be lots of $$$. If Im not in pain, should i not worrg? Clearly im concerned, but after having a perfectly fine bean with a strong HR and stretching all about a week ago Im not too concerned. If I have pain id go, but my question is- what could be happening??