Number 2 problems?

So I'm currently 36 weeks & 1 day with my first child. I have had problems going number 2 since I found out at 5 weeks. First was really soft almost like diarrhea, then constipation, now I feel like I really have to go but only a little bit comes out but feels like more. And now when I try to bear down, I feel this tightness in my lower back & it's so uncomfortable that I can't go all the way. Does this happen to anyone else? Please say yes! Anyone?