What should I do ?

My daughter is 4 months old … but for some reason I haven’t had a period since I gave birth I bleed like a week straight after having her ,. But since haven’t had any bleeding nor period .. the past few days I haven’t been feeling myself .. feeling sick and like I’m going to throw up ,me and the husband had un protected sex on the last day of august . Took a test and it came back negative.. should I call my doctor about not a having a period ?