I have been tested for STDs and HIV and everything came negative. But I have anal itching while wiping, washing, or after intercourse.?

Exam. Anal itching is a common problem. Hemorrhoids or small tears can cause this. Cheap toilet paper and certain soaps can also cause. Try an over the counter hemorrhoid cream that contains steroids to see if that helps and schedule a visit for an exam.
See below. You might have hpv, or possibly a yeast infection or a hemorrhoid, but do get this evaluated by your doctor soon.