Seems like your husband has developed an allergic reaction
to the tattoo.
First of all, you need to avoid applying any oils or creams over the affected area.
You need to apply a topical steroid
cream over the affected area twice a day.
Give some oral antihistamines for the associated discomfort and to decrease the allergic reaction.
Since your Husband has developed an allergic reaction this time, so there is a high possibility that he might develop such reactions every time he gets a tattoo done.
Hope it helps
Dr Geetika Paul.