need help(advice)

I am currently 37 weeks and my back has been hurting for at least 6 or 7 hours after I came back from walking. Feel nothing but pressure in my lower stomach when I stand. I've tried soaking and that didn't help. I've tried water and changing positions whether it's standing up or sitting down and nothing or helping. Didn't want to go to the hospital becuz I figure it's just normal and I have an appointment in the morning. But I'm just experiencing a whole lot of back pain that won't ease up.