Leaking Coolant

I did mean the oil pan plug. I'm having a hard time pin pointing the leak because it happened after I filled the radiator up. One day I added a couple of gallons but it wasn't enough to fill it. There was no leak. The next day I filled it up the rest of the way to top. I didn't notice the leak until the next afternoon. The floor was wet under where the starter connects.I've checked all hose connections, water pump, etc.... and they were all dry. The top of the starter was wet. I also checked freeze plugs but I don't think fluid would leak into the pan if a freeze plug leaked but am by no way a mechanic. I'm learning everyday. And this lesson has been the most painful so far. Should I be draining out the radiator? Am I hurting motor now that antifreeze has leaked through to oil pan?