what can it be? sharp discomfort that comes and goes.. at peak fertility PLEASE HELP

Ginger
On my 5th fertile day which is also my peak been using preseed and baby dancing my question to anyone that may have experienced this I'm having sharp cramping I don't think it implantation but it feels like sharp pains in my uterus area and it comes and goes it catches me off guard like wow.. some people know they are pregnant sooner and some say it could be implatation has anyone experienced this.. please help