Oil is leaking badly..

2 days ago when I got gas in my car, there was a puddle of Oil, I check for leaks but couldn't find any, and also check the oil plug but couldn't tell. Any Suggestions?

Are you sure the oil wasn't there before you got gas? Have you seen a puddle elsewhere? If so what part of the engine does it seem to be coming from? It could be a rear mainseal, bad sending unit, bad oil filter and etc.
If it is a bad sending unit above the oil filter you may not see a leak with the engine shut off. Check and see if you can find a general location of puddle and post again!

it could been there before, I don't know. That puddle of Oil was fresh though.

when I got home I checked the oil last night, but it was kinda low. It could be anything. So far I haven't seen no leaks yet. so who knows.

Keep checking the oil. One way to see if your car is leaking is to place clean cardboard under the car and start it up. Let it run for a period of time and then shut it off. If you notice oil on the cardboard then look at the location you found it and note that. Then check the area of the engine where the oil seemed to be coming from. If you do have a large leak the you should be able to track it down very easily.