Contact Dermatitis: The patient's report of the rash starting after using Zepbound (a cleaning product) suggests a potential allergic or irritant reaction, making contact dermatatitis the most likely diagnosis. This condition is characterized by skin inflammation and rash due to contact with an allergen or irritant.

Allergic Contact Dermatitis to Other Substances: Besides Zepbound, other substances the patient has come into contact with could be causing the allergic reaction, such as metals (e.g., nickel), latex, or certain plants.
Irritant Contact Dermatitis: Similar to allergic contact dermatitis but caused by a non-allergic, direct irritation of the skin by a substance, which could also be Zepbound or another chemical the patient has been exposed to.
Insect Bite or Sting Reaction: Although less likely given the linear nature of the rash, an insect bite or sting could cause a localized reaction that might appear linear if multiple bites occurred in a line.

Erythema Multiforme: A skin condition characterized by target lesions, which can sometimes appear linear. It can be triggered by infections or medications and is important to recognize due to its potential severity and need for specific treatment.
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN): Although rare, these are severe skin conditions usually triggered by medications or infections. They can present with skin lesions and are medical emergencies due to their high morbidity and mortality.

Linear IgA Bullous Dermatosis: An autoimmune skin disorder characterized by blistering skin lesions that can sometimes appear linear. It's a rare condition but important to consider in cases where common diagnoses are ruled out.
Phytocontact Dermatitis: A rare condition caused by an allergic reaction to certain plants, which can result in linear or streaked rashes if the plant comes into contact with the skin in a linear fashion.