What Causes Spotting, Nausea And Mood Swings While On Depo Injection?

I m on the depo shot and have had unprotected sex, and i believe i may be pregnant. i have been showing alot of symptoms. these include mood swings, alot, peeing alot, fatigue, spotting (and i don t normally have my period on depo), and i feel sick like I m going to puke, like after i smell certain foods but haven t puked yet. And the list goes on, what do you think?