What is wrong with me

Kathleen • 26. Married. TTC baby #1

Not sure what is going on.....

So tonight I'm on my cycle day 7 so definitely not pregnant! But I had a VERY sharp pain in my belly like right in my belly button and I'm not sure what it could be caused by... I wore tighter jeans to work with my belt but I wear it all the time and feel fine ... not sure what going on its subsided but now I just feel nauseous.... any idea?