Just found out I'm pregnant but..

I just found out I'm pregnant but I feel like any min now I'm going to get my period. My backs been hurting off an on nothing sever kinda just uncomfortable an my lower abdomen just feels like when your about to get your period I'm only 4weeks an 5 days is anyone else feeling like this. I was supposed to get my period Monday an I read that at this early your body sometimes is still confused an thinks it's going start your period hence the feeling of starting your period even though your not going