What Causes Bloating,abdominal Discomfort,indigestion And Nausea?

I am 26 years old. been trying to get pregnant for 3 months, had sex every day during my fertile period for 3 months and am yet to be pregnant. I had my last period on February 21st and now am in my fertile window but experiencing bloating, abdominal discomfort, indigestion and nausea sometimes. I didnt use to experience these symptoms while ovulating before i became sexually active. What could be the cause?