please tell me what these abdominal tightenings might be! I am on CD18, I think I ovulated on Cd13. and now, rather unusually for me I am getting crampy type sensations in my abdomen, which I always get before AF but not usually til about CD24/25. Could it be a sign an egg has fertilised? Now this is the ridiculous bit - the SA results we got last week said no sperm present...this is psychosomatic right?!