After a very difficult term, fraught with many negative issues between myself and the leadership team. I have secured a much-wanted new job. However I am off sick at the moment and my Head is trying to start an investigation regarding my absence. He hasn't yet returned the reference to my new employer. I am extremely concerned that the new job may be revoked should he write in the reference that I am under investigation. The union are involved and are furious that I am being hassled whilst of sick. Any advice greedily accepted.