Negative pregnancy tests

Hi! My BF and I are ttc a rainbow baby. These online forums have been really helpful in this healing process. 
I took a pregnancy test today, one day before my period is supposed to start as directed by Glow and it was negative sadly.
I have been cramping for a week now but today I had a stabbing pain that was the same pain I felt a few days before I found out i was pregnant the first time back in December last year.
My questions:
1. Has anyone else felt this stabbing pain before? This pain is very unique and was so bad it stopped me in my tracks. 
2. When should I take another pregnancy test?
Thank you in advance to anyone who responds.