Bewytched - Matilda Kavanagh, #4

Valentine's Day is coming and for Witch for Hire, Matilda Kavanagh, that means the busiest time of year for her little business of potions, spells, and charms. But someone is trading on her name and their products are having disastrous results. Mattie's gotta find this impostor and stop them before things get out of hand. Poxes and boils and uncomfortable rashes, Mattie can cure, but when it's a matter of life and death, it could ruin her business and her love life - what's left of it anyway.
So much for worrying about finding a Valentine to spend the night with - Mattie's gotta find a way to save her hide.