Contractions at 21 weeks....

Have any of you have been having contractions.... I'm 21 weeks and was diagnosed three weeks ago with a two tears in my placenta. Since then I have had a very bad cramping but the past day I was cramping and feeling different way worse in pain. Went and got an ultrasound today and they saw the tears slightly bigger but also saw that I am actively having contractions. At this point they say there's nothing to do but wait to see if they get worse and/or wait till next ultrasound with high risk dr. Has anyone experience painful contractions this early?! Thank you all