Lower abdomen cramp, is it a bad sign

Is it something to worry? My lower abdomen cramps mildly. Is it normal to have mild cramps at week 3/4? My period should come next week as I am 5 weeks cycle period, but I found out I am already pregnant. I had history of chemical pregnancy twice and all I remember was bad cramp and period came right on time and I lost the baby. I am now on duphastone hoping to carry the baby to full term. I worry it’s another chemical pregnancy.. Can any mummy who has successful pregnancy share with me if the cramp at lower abdomen is normal?