Yes, the pill can cause nausea. Pick a consistent time of day to take it at, either morning or night. Some people can't take it at night, and some people can't take it in the morning. I personally found I was not nauseous when I took it in the morning.
This is usually a temporary side effect, so give the pill three whole months as you're supposed to. That's how long it can take for side effects to go away.