Take this picture to a plant nursery and ask the plant professionals. I venture to think it is a virus but I have no idea what you would do about it. It might be normal coloration. There are tulips called Rembrandt tulips which are multicolored due to a virus that lives on them. I believe there are lilies like that too. Again take the picture to a nursery.

It is a White Ghost Candelabra Plant, Euphorbia lactea

Just a few weeks ago it was fine and beautiful but not it has strange rings (brown filled with pink edges) and brown spreading patches. I've already looked online a little and couldn't find anything like it. Please help. I really like this plant.