Assessment of water damage to ceiling

Hello - we had a leak from the flat upstairs cause a couple of stains on our ceiling. It seemed to be a small leak that they’ve fixed, and there wasn’t any dampness on our side, so we figured a bit of paint would fix it up. Now we have a crack appearing through one of the stained areas and are more worried about damage up in the ceiling, but aren’t sure who to call - carpenter, builder, plumber?

We’re looking for any recommendation for someone who can give us an idea of how much damage may have been done, or if this is something that just needs a quick swipe of plaster and coat of paint. The source of the leak was repaired, so no worries about finding/fixing that.