Earlier this month, my boyfriend and I had unprotected sex. We are trying to have a baby but two days ago I started menstrating. Normally, between the first and third days of my cycle I am "heavy" but this time, I am very light. I have been getting cramps in the center of my belly and my lower back (i normally get menstrual cramps on my sides and lower belly). i've been feeling nauseated around mid-afternoon/early evening. I am a social drinker but I never throw up after drinking till now. Could that be a sign that maybe I am? How long after having unprotected sex would be best to take a home pregnancy test and is it possible to still be pregnant but menstrating at the same time?