Why is my Buick Regal oil light still on?

I own a 2004 Buick Regal. A few days ago, I changed the oil and oil filter in it. Just today the light was turned on when I was driving home. I had no idea why, but then it turned itself off. I was relieved until it started again. It has been doing this pattern all the way home. Do you know how to fix this? Should I get a new car because I have had many other issues with it recently? Help!