Spotting thru whole pregnancy

Hey I just had to post this because I'm not finding any info anywhere. This is my 4th pregnancy and I have been spotting the whole time! My obgyn said its nothing to worry about, so I have been trying not to worry. But 2 days ago I left work early because I was actually bleeding red and called my obgyn and they sent me to the ER. They said everything looks fine and baby is actually a week ahead. So they said I am at 15 weeks. They don't know where the blood is coming from but they didn't seem to concerned either. Has anyone else had this? I'm silently freaking out.