Hi, I can understand your concern for the red bump on arm which looks like a bug bite. I can make the possibility of ingrown hair or folliculitis . It can further be aggravated by heat and humidity with sweating over this area. It is generally painful to begin with or have a feeling of discomfort. It generally begins as reddish dot and then can enlarge later on to form a cyst. The most important thing you should do is to not touch, pinch, pop or squeeze the area by any means. Stay away from hot and humid climate. Wear cotton clothes and cotton undergarments and especially change the undergarments two times a day. Apply fucidin cream or mupirocin cream over the affected area and take pain killer like paracetamol or diclofenac. Oral antibiotic may required such as ciprofloxacin 500mg two time for 5 days under medical supervision. Take care