Hello, I can understand your concern for the rash on neck with numbness. There can be multiple possibilities f the rash and it requires thorough physical examination of the area. You have also not told your age and sex along with important medical hstory of any other problem so that we could have helped you better. In your case it can be herpes zoster or an insect bite causing the problem. I suggest you to not touch the area at all and do not try to scratch it. In my patients with your kind of problem I prefer to give an antibiotic cream to apply. An antihistamine like cetrizine can be taken for itching problem. All the best.