Are you on any medications?
The neck rash
could be due to several causes. You would need to see a
skin specialist to rule out eczema, sweat dermatitis, heat rash, acne, folliculitis, etc.
You could take some oral antihistamine or antiallergic medications like loratadine or cetrizine and see if it helps with your symptoms. Apply calamine lotion at the site of the lesions to help soothe the itching.
What other symptoms are you having? Since when have you noticed the lesions?