I have been on the depo shot for a little over 9 years and I always have my period before the 3 months are up and I always get it on the 1st day they set it. But this time I went and took my shot later that day I started getting Pressure In The Stomach. Yes around 3 weeks before my shot was do I had sex unprotected but I did a home pregnancy test before I took my shot and it was negative so what could it be also I have been peeing more and my back has been killing me.