I'm Very Scared. My Husband Of 30 Years Has Developed

I'm very scared. My husband of 30 years has developed this mottling on his leg that I noticed, and I marked off with a sharpie, to see if it gets bigger. Please help, I can't live without him. He is my life. It looms like lace, and is red. Wish I could post picture, but there's no attachment button. Its about 8"x3" on the left side of his right calf muscle. ........ At 10:30pm, I took a picture, and dotted it with a ssharpie.Now at 1:00am, it is all gone. What could of happened? ?