What a poor little bugger! Victoria!!!! Exactly how much of the visual damage occured/ increased whilst in your possession in the last 2 weeks. Its possible a bacterial, viral, fungal infection has struck the plant and seems by the pic its in the crown. Looks so similar to a Phal. Cell damage from sunburn, pest attack can also result in this way once the bad pathogens have entered a vulnerable area. Hope someone on here can verify it for you from their experience. If its viral its sadly doomed and hope your other resident plants are well faraway. Poor little Aerangis.