28 wks, 5days preg, mild cramping and light spotting.. help?

Last Thursday I wound up being in severe pain and was bleeding. I was in the hospital overnight and monitored but there was nothing wrong. They ran a bunch of tests and did 3 different ultrasounds but still nothing. Just now, I got out of the shower and went to dry myself off and again had some blood there. I've been complaining about my belly hurting for a day or so now but the baby is still moving around. (He's a bit of an acrobat.) I've lost a baby at 19 wks before so I'm just a bit jumpy with anything. Is this something I should be worried about? Thanks in advance.