I am currently using the contaceptive injection as my birth control, but my periods have been all over the place ever since I started the injection method, which I expected.. I am due for my 3rd injection by the 31st October, I am having it tomorrow, I was supposed to come on my period 2/nearly 3 weeks ago but I haven't been panicking because my nurse told me that the injection may stop my periods completely at anytime using the injection, but I am getting bad period pains as if I am about to come on but I have had these for the last week or so, should I worry if I am pregnant or not?