When body first come in contact with sperm...

Hello, very new here and we just seriously started TTC about a month ago.  This is the first time in my life allowing ejulation in me and the days (1-2) following some BD almost make me feel nauseous, like a bit off, and with this bubbly feeling in my stomach, or maybe that's my uterus?  Is there such a thing that my body is rejecting or questioning what the sperm is doing in there?