I thought there might be a possibility that I am pregnant so I took the emergency 72 hour contraceptive pill.
I felt fine for about 5 days, then I noticed I've been spotting like I'm on a light period and feeling very nauseated.
Are these normal side effects from a contraceptive?
Or am I pregnant?

Yes, you are either having side effects or you are pregnant. There is no way to know for sure. It can be either. The pill is not 100 percent effective, and less effective the longer it is taken from the act of sex.

How long after the possible intercourse did you take the pill? The longer you wait the less effective they are. Their purpose is to keep an egg from implanting if it has been fertilized.

You should follow up with your doctor if for no other reason than to put your mind at rest and to discuss other forms of birth control.