As per title. We moved into a house 14 months ago with a brick lean-to added to the rear of the property. 

Yesterday evening I noticed a crack had appeared on the wall across the render. We’re not out in the garden often at the moment given the weather so I’ve not noticed it before, and I’ve checked some videos we made of the house from when we viewed it last April and it definitely wasn’t there before. 

The crack is about 2mm across and I can’t see any evidence of it inside the lean-to or anything like buckling of the roof beams on there either. The wall around the corner has a wooden beam attached across where the crack might be so I can’t tell whether or not it extends around the corner either. I haven’t found any cracks on the wall of the house itself yet. 

I’m obviously pretty concerned about a new crack appearing on our house, especially since from a very cursory internet search I’m led to believe a zig-zag crack could be a sign of subsidence. We’re first-time homeowners so I’m feeling a bit out of my depth here - what type of person do we contact about this? A structural engineer, someone else? Obviously hard to tell from just one photo but does this look serious from the photo and description?

Sorry also if this is the wrong subreddit for this. 

P.S. the spider is as far as I’m aware not load-bearing. 

Crack appeared in wall of lean-to, exterior only - advice needed!