Worried... need advice please


I'm 25+4 and today I spent my day cleaning the whole house. I've been pretty sedentary this pregnancy and it was an effort... I had few braxton hicks here and there, because I didn't drink enough water but nothing too bad. Thing is, now I have lower back pain. And I never had this. Not during pregnancy, not when I was on my period, not when I was tired. And I heard so many stories about preterm births that started with lower back pain and I am so worried..... Haven't felt the baby since this morning but now she is pretty active. I don't know what to do... Should I call my doctor? I don't have cramps or anything, it's just the back pain