weird twinges and spasms? help!

okay, this is baby number 3 for me. I'm 18 weeks and 6 days as of now. last time I had a baby was almost 6 years ago, so it's been awhile. but anywho, i've been having these weird pulsing/spasms, like in my vagina. it sounds odd when I try to explain it, and it's only at night when I lay down for bed. it seems like it's on the other side of my cervix? I feel my baby move, idk if maybe it's hiccups or idk what it is. does anyone else have this or know what it is?