I have had this echeveria for 3 years now. It has grown a lot. It is kept outside in a very sunny spot. We are in Redwood City, CA. It has suddenly developed these brown spots. It was repotted last year and it has overgrown its current pot, but I don't think the spots are because of that. Would this because of the cold? It has been cold at night (50F) here these days. Is this scales, what is the best way to treat this.