Lower back pain.

Becky

I am 5w3d today,and i am having some back pain. Actualy i was for shopping with my MIL for around 2-3h(we are celebrating a birthday tomorrow),and you can imagine only walking. I got kinda tired. Do you think its for tirednes or should i be concern. Also: sorry TMI..i had some very light amount of brown spotting today. Any of you experienced the same?