Assuming the photo is fairly representative of the entire firebox, what's it going to take to repair all of the mortar joints in terms of time/cost? The width at the back is 24, the front is 30, and the height of the area needing repair is 30.
When dry skin is the cause of an itching back, it is easily remedied by applying a lotion or cream to moisturize the area. When chronic dryness and itchiness is an issue, a person may need to increase hydration efforts.
Dry skin. This is the most common cause of total body itching and is especially likely in the dehydrated air of heated winter interiors. The main danger of such itching is scratching, which can lead to skin infections caused by resistant bacteria.