Confused

So I just started birth control again after being off it for about a year. Started it March 20,2019 this is my first month on it. I accidentally missed it the 4th of April. An before I missed it I was getting little sharp pains in my lower stomach but they went away an now I’m a week before my period is supposed to start. An I have these cramp like feelings. An have been sporting every morning very light for the last 2 mornings. Very nauseous. Do you guys think it’s from missing the pill or what?