I agree with above. I was in L&D 2 days ago due to severe menstrual like cramps and they were keeping my focus that I didn't even notice I was having contractions every 2-3 min apart. It could be something as simple as that. It could be round ligament pains. Better safe though. Specially since you were dilated to 3 already, this could be it! If you want, take a 15 min warm bath and see if it helps. If it doesn't, go in. Worse case scenario, you will relax a bit before going in, right? :) Did you lose your mucus plug already? Wondering if that discharge could be pieces of that. Keep us notified!!! :)
When in doubt check it out. Better to be safe then sorry waiting to long to go :) good luck let us know. If you were there cpl of days ago and having all that is really go get checked.
I'm not sure, but I would go back in. You may have dilated more. So I would go in because this may finally be the real thing. So you should go.