Please, Help a girl out. Would ya?

Took plan b about 5 weeks ago. I took the pill an hour after the incident.  My period came a week after taking the pill. Some morning I wake up feeling uneasy/ nauseous and I am really worried about being pregnant. My stomach has never felt like this before, so I am worried. Is it the side effect of the pill? I feel normal other than feeling Like there is something in my tummy. I don't notice any other sign of pregnancy besides feeling nauseous. Please Help!