i’m 35w 4d and lately i’ve been in and out the bathroom constipated with Cramps,bad lower back pain,

& Mucus in my stool .. Today i used the bathroom 4 times so far, i told my doctor my symptoms and he told me to try benefiber, but they were out so i’m trying the metamucil, Anyone has or have had this problem? this is my first pregnancy so i am a little worried about having to go to the bathroom literally 3-4 times a day the past week, idk if this is normal during late pregnancy but any advice on taking it?