I'm thinking yellow leaf tomato curl, I've had an issue with whiteflies recently, I'm going to yank it out unless someone can suggest otherwise.

Thanks

Or herbicide damage. Possible drift.

suggest you contact your county's Extension Service office to determine what's the problem in your area. To locate the office use this interactive map:

http://npic.orst.edu/pest/countyext.htm

Sorry for late reply. You're in Florida and I am almost certain it is tomato yellow leaf curl virus, usually from whiteflies that carries it. This is basically death to the plant since it won't produce anything worthwhile once it has it.