What Causes Spotting,swollen Breast And Mild Cramps After Taking Nuristerate?

Hello Doc,I took my first shot of the nuristerate on february the 25th and its a 2 month one,my next appointment is on the 22 of April...I had unprotected sex on the 20th of march...I want to know how long does it take for the nuristerate to be effective in my body,I havent been on my periods since the shot but I have had spotting...Could I be pregnant????,my breasts are a bit swollen,some food really dont smell good that they cause me to want to vomit...Im not eating well and I stil have cramps like period pains and my tummy hurts .....im starting to freak out,should I go take a pegnancy test,or does nuristerate symptms come different to people please help