Well, Steve, I'm afraid you are right - two weeks later (room all finished now) and the crack has reappeared. I really don't know what to do now.
I had the ceiling artexed 10 years or so ago - it must have had a crack then otherwise I wouldn't have had it artexed.
The artex was still in good condition (no visible cracks) when I started the room a couple of months ago - I knocked out a built-in wardrobe leaving scarring on the ceiling where the wall and top-frame were, so I had the whole ceiling skimmed.
The thin crack appeared after a couple of days (nowhere near the site of the old built-in wardrobe). The plasterer's first repair (digging out crack and covering with easyfill) didn't work, so he came back, taped up the crack, and re-skimmed - I watched him do it, it seemed like a good job to me. But now the crack has reappeared.
The bedroom is on the first floor and there is only a loft above - no-one's been up there, so there's no change there. The only thing I can think of is possible upward movement/flexing when the weight of the old block-built wardrobe and bedroom furniture were removed and downward movement/flexing when the new fitted bedroom furniture was installed, but I am guessing>desperate.
Any ideas? Is there any flexible paint I can use to cover the crack??
. You`ve now got a ceiling that is - plastered originally - then artexed - then skimmed again twice - am I right . That`s a lot of weight now working on the edges of that crack . And the crack is probably from the original nailing up of the ceiling board , it wouldn`t be screwed back in the day . You Might get away with re boarding a section along the crack , but I think it might need a complete re board with LONG screws to get through the layers - and looking in the loft to acertain where the crack is in relation to the boards . If the crack is where the boards are joined along the ceiling joist , you might get away with a long nogging next to the joist to support the ceiling , then do a decorators fill .