Headaches,lower back pains,lower stomach pains,period like cramps

Unlikely to get pregnant while on your period, but it is not impossible. Some women will have sex during their period, and if they ovulate soon after, pregnancy can occur. It is not the usual time for most women to ovulate, but as your body adjusts, cycles may be off. Some women will get pregnant fairly quickly after their last shot, while other women won't be able to get pregnant for well over a year.

Your symptoms are the same that many women have during their period, so they do not necessarily indicate possible pregnancy.