Tiny red itchy bumps on the arms and stomach are commonly caused by heat rash (prickly heat), sweating, skin allergy, irritation, or sometimes mild fungal or allergic skin reactions. Hot weather, excessive sweating, tight clothing, and occasionally certain foods may trigger or worsen itching in some people, although mangoes alone are not usually a direct cause unless you are personally sensitive to them. Since the rash is itchy and causes irritation, it is important to keep the skin cool and dry. Wear loose cotton clothes, avoid excessive sweating, and take cool showers if possible. You may continue an antihistamine like Allegra if it was advised by a doctor, as it can help reduce itching. However, Fungnil-B cream should not be used for every rash without proper diagnosis, especially if it contains a steroid, because steroid-containing creams can sometimes worsen fungal infections or irritate sensitive skin if used unnecessarily. Instead, using a mild calamine lotion or soothing moisturiser may help relieve discomfort. Avoid scratching the bumps, as this can increase redness and irritation. If the rash spreads, develops pus, becomes painful, is associated with fever, or does not improve within a few days, you should consult a dermatologist for proper examination and treatment. A doctor can determine whether it is heat rash, an allergy, a fungal infection, or another skin condition and suggest the correct medicine.