What Causes Lack Of Menstruation 5 Months After Childbirth?

I gave birth 5months ago and I have not had my period. Bit confused because im not sure if symptoms im experiencing are pregnancy ones or my period is coming. About 2weeks ago I cramped alot and thought its my period but nothing. I still don t have a period and I get sharp pains on my sides. Can I still get pregnant without a period?