Thanks both
Much to our surprise, tonight we changed our minds on the vet visit. As Calypso has settled in she's been a bit reclusive but tonight she's clearly realised she's safe and she let us watch her potter around her tank for a good few minutes. If we hadn't known the head tilt was there we'd not have seen she had any issues. I then accidentally upset her a bit (was noisier than I wanted to be sorting something in her cage) and suddenly the tilt was back. We really do feel that all the signs are pointing to it not being an infection at the moment. As ever we will keep watching her closely but we're really hoping it'll clear up on its own now