Had unprotected sex 20 june, got cycle next day is it still possible i cld be pregnant. been feeling tired and slight cramping can u get sym already?

Almost certainly not: When your period comes, it takes the contents of the uterus with it. All the soft tissuey bloody lining that would have been a place for the fertilized egg to implant flows out and with it, any loose egg - so essentially the necessary parts are no longer there. If you want to prevent STDs or pregnancy don't rely on this - use protection. Take care!