You need to either check the pressure or get a new oil sender on asap to make sure the oil pressure really isn't low. Then, assuming the oil pressure is ok, you need to find out exactly where the leak is coming from. Clean the oil from everything you can reach in the bay and also underneath, run it for just a minute, and then check for oil. Repeat until you find it. If it doesn't leak anymore, then it was the sender that had been leaking.
Or, if you don't DIY, take it in and hopefully a mechanic can find the leak right away, after checking to see if the pressure is ok.