Hi, I Am Taking Primolut Since Last 15 Days To

Hi, I am taking Primolut since last 15 days to delay my periods. I took three times a day for first 3 days and then switched to twice a day. I have to continue taking it till Saturday. I am having some abdominal pain and feel pressured. Lately I feel Nausea and Diarrhea. It feels like I might be getting my periods. What should I do? I have enough medicine for twice a day. My friend gave me Regestrone. Can I start taking that along with Primolut? I appreciate your help. Thanks