Random Spouts of Crying

Oh my lord this is my 4th pregnancy and I keep getting these random moments of needing to cry! Like I can't help it and it's not over anything really. There was one time after my SO gave me a hug in bed, another after the doing the dirty. And just now after my son knocked me in the mouth with his head. It wasn't really that bad nothing to cry over but boom insta tears and weaping that I can't hold back. I have never gone through this whole hormonal bit with my prior pregnancies and it can go away any time now.