i had my nexplanon removed almost 3 weeks ago. I ovulated about 4 days later and had unprotected sex the day before, i cramped like 3 days later but didnt start my period. Since then ive gotten a few bad headaches, feel sick, smells kinda make me feel sick, lower back pain, lower abdomen feels like its stretching/ cramping, constipated, and tired alot. I have taken several test all have came back negative could it just be to soon to test?