Tendstim item is your healing item in this game, available Abbot Roo & some other places. Healing Ointment is targeted in accessories - applicants to reduce sexual wear.
NPC do also heal over time when you rest overnight, which may or may not be relevant to your game
If you move to inventory->accessories, on the lower portion is a toggle between accessories & applicants. Activate the applicants area, and then a "use oitment" bar will be next to any area that has wear, the bar will highlight red if useable & then just click that and it'll perform it's effect.
