Pressure in back and side

Has anyone else had pressure kind of in their back and sides? I've been having regular pressure from baby dropping but never pressure in back or side until today. I have been starting to get out and walk more since I'm 36 weeks. But it hurts to walk now because of this random pressure. I do have an appointment tomorrow. First time mom so everything is new to me. I also haven't been able to sit right for a few days due to having pains in my butt bone area.