What Causes Sickness Every Night After Started Taking Cilest?

I've been taking antidepressants (sertraline) for around half a year and last Thursday I started to take cilest to help me with my period pains, but every night since then I've felt sick. I'm fine during the day but it gets to around 8 pm and I start feeling sick (I actually threw up earlier), my mood completely drops and I just want to cry. Any help would be great