Sharp Pains

I stood at work all day and then went for a 1 mile walk and I've been having Braxton hicks all day. I was almost fully effaced and 1.5cm dilated and he was engaged, OB said that he can come at any point at my last appt. I feel him extremely low and I keep having sharp pains in my lower stomach, not lightening crotch. Any idea what this could be?