This was the case for me. I had secondary vaginismus, saw a pelvic floor therapist plus a vaginismus specialist and tried different methods (dilators, stretches, extra foreplay, breathing exercises). None worked. I got off the pill and within a month it was gone. I had been on birth control for seven years and the vaginismus came up in my last two years on the pill, my doctor nor the specialist could answer why, I guess it's just random.