Problem after masterrbatting..help plz..?

when i sqeeze in my vagina muscle as if im holding urine now,theres a heartbeat feeling as if a penis is going out and in,,....it feels like it gets tighter then loosens as the movement builds....im upset b/c i thought masterbating had no effects...will the feeling go away...i masterbated yesterdaay and i still have that feeling...........b/c i was having a in orgasm ....so it felt like i has a loose stool with urine...wierd huh......as i stick the vagina muscle there in...it feels like it gets tight when i squeeze it then it let goes and the same thing reiterating...pz help