Unexplainable Scab Please Help

My cat I love dearly developed a weird Scab on his stomach and his right shoulder. I looked up every possibility but nothing made sense.
This is a picture of the scab on his stomach. It's not a normal Scab and honestly it scares me. I just want some people's opinions on what it could be before I go to the vet with it because I really cannot afford it, but I will. Thank you

I'd have a vet take a look at it. Please look into low cost vet clinics in your area. This article has tips on affording vet care: http://www.thecatsite.com/a/no-money-for-vet-care-how-to-find-help-and-save-your-cats-life Vet bills can be pricey, especially at a full service vet clinic / offic and at a vet ER, so pelase try to save money at least have a plan on how to afford vet care when your cat needs it.