period and the shot

I've had my shot for almost month now (I was on my period when I got the shot) and I waited 2 weeks after my shot before having unprotected sex but we pull out because it makes both of us feel better. I'm due for my period (tomorrow the app says but I've never really had a regular period) and I'm having period like sysmptoms (thighs hurt, low back pain, slight cramping, and little nauseous). The thing that's getting me is the nausea, it's not sever and I'm not throwing up and I can eat and everything.  I've had this as a period sysmtom in the past but is this normal should I be conserned. I think I'm over reacting but I'm the type to over react.