Got itchy red bumps only in the areas i applied johnsons baby oil. taking allegra 180mg in the day & benadryl (diphenhydramine) 25mg at night. when will rash go away?

Soon: It sounds like you've had a contact dermatitis/allergy reaction to the baby oil. Unfortunately, that specific baby oil contains an ingredient that metabolizes into formaldehyde, a toxic chemical that can trigger reactions like yours. The Allegra (fexofenadine) will help, but topical Hydrocortisone found over-the-counter will likely help even more. I'd apply it twice daily.