It sounds like your mother experienced an allergic reaction, likely to the diclofenac or paracetamol in Diclozon, which was fortunately relieved by pheniramine (Avil). Because her immune system is currently recovering from this allergic event, it is safest to postpone her second COVID-19 vaccine for a few days. She should be completely free of allergic symptoms and off antihistamines for at least 48 hours before getting vaccinated. Please consult her doctor to safely identify the specific drug allergy and to get a green light for her vaccination.

Since your symptoms returned after Avil (pheniramine) wore off, despite using Cetaphil and coconut oil, this might be due to nocturnal pruritus. At night, naturally occurring changes in body temperature and skin moisture can worsen itching. It could also suggest a condition like chronic hives or a localized nerve sensitivity. Because the itching is worsening, it is best to see a doctor. They can safely evaluate you and suggest longer-acting solutions to help you sleep comfortably.

Your daily symptoms suggest allergic rhinitis or nasal sensitivity triggered by sudden temperature changes from cold water and air conditioning. While Avil (pheniramine) is effective, taking it daily long-term is not recommended, as it can cause drowsiness and lead to tolerance. For daily control, non-drowsy generic antihistamines like cetirizine or fexofenadine are generally safer and more suitable. Please be reassured that this condition is highly manageable. I encourage you to consult a healthcare professional to tailor a safe, daily treatment plan and discuss allergen avoidance strategies.

Taking more than the recommended dose of Avil can cause side effects like drowsiness, headache, nausea, or vomiting. Since you had discomfort, vomiting, and headache, stop taking extra doses and drink plenty of fluids. Rest in a cool, quiet place and monitor your symptoms. If vomiting continues, headache worsens, you feel very drowsy, or have trouble breathing, seek medical attention immediately.

Please reassure yourself that this is highly treatable. While Avil helps temporarily ease the itching and Nevlon soap keeps your skin hydrated, they cannot cure the underlying cause. A contagious rash spreading among household members often suggests a condition like scabies. I strongly recommend that you and all family members consult a doctor together. You will likely need a prescription medicated cream, such as permethrin, applied simultaneously by everyone. Additionally, washing all clothes and bedding in hot water is essential to stop the spread.

Because pheniramine (Avil) did not bring relief, this rash is likely not an allergic reaction. A painful, burning rash preceded by skin sensitivity on the neck and chest is highly suggestive of shingles (herpes zoster), which is a viral reactivation. It could also be a localized skin irritation. I highly recommend having a doctor evaluate this promptly. If it is shingles, starting generic prescription antivirals like acyclovir or valacyclovir early can greatly speed up your healing and relieve the pain. In the meantime, cool compresses may help soothe the area.