I had unprotected sex on april 15, 18, & 22 i started being constipated i feel gassy i have on/off cramps and slight headaches can i be pregnant?

Maybe, but...: Today is April 24, so sex in the preceding week would create no symptoms from a new pregnancy. If newly pregnant, symptoms won't start until another 2 weeks later. Unless of course, one was already pregnant from last month (if one missed her period between last month and now). If worried, a home urine pregnancy test is very accurate by 3 weeks after sex. They are sold in stores everywhere.