Living near Rendlesham forest I've had my fair share of unexplained noises and I always try to rule out the mundane first. Scratching in walls is one of those sounds that gets under your skin though, literally keeps you up at night wondering.
What did you actually find in the end? You've left us hanging with that title.
I ask because a few years back I had something similar in the loft space above my bedroom. Went on for about three weeks, always around 2-3am. Eventually found nothing. No droppings, no entry points, no animal. My neighbour suggested it might be the timbers contracting in the cold but it didn't sound like that to me, it was too deliberate.
Never fully explained it. Part of me is fine not knowing, part of me isnt. Curious whether yours had a rational answer or whether you're posting here because it didn't.