Im having a naightmare with this car

I seem to be taking one step forward and two steps back.
Ive gone out in the car earlier and car was driving fine, went over a speed bump a little bit too quick and heard a wallop.
It was nothing extreme and i wasnt exactly doing 90 over the f**k*r.
But i drove it about 3 miles and had the..... "STOP, OIL PRESSURE TOO LOW ", light come ontothe panel and an oil light came on.
I drove the car home and just went out to check the oil level once the car had gone cold.
This is when i was greeted by an oil leak, i had a look and can see it dripping from somewhere but dont know exactly where as i cant get under the car to check.
Could anybody tell me where its likely to be coming from and what could be my problem ?
All help appreciated
p.s.... as you know by now, im not very mechanically minded so im clueless apart from looking on the net.