Suggest Treatment For Headache And Nausea During Periods

hello, my cycle has been every 29 days for the past 3mths but always the same about 6 days, this mth it was only 3days and brown and very light just a couple drops a day, I am having cramping, dizziness, neasuea and headaches as well, I had unprotected sex on my last day of ovualation, but I also started taking St. Johns wort that same week but it doesn t seem like I was taking it long enough to have a side effect like that Since I have only been taking it a couple weeks. so I am unsure if my irregular cycle could be pregnancy or a side effect of the st.johns wort.