I have these occurrences of colorless bumps about the size of mosquito bites that randomly appear on my face. They have no puss or anything. They're typically on my forehead and sides on my face near my hear line, on my chin, and sometimes even on my neck or behind my ears. They normally appear in small clusters of about 2-6 bumps, sometimes just one or two clusters and sometimes four or five. They generally go away, but the time varies. Sometimes it's been 20 minutes, and sometimes up to 3 hours, but it's typically around an hour. One time a few bumps stayed there for almost a day. Sometimes they are itchy and they really bother me. This occurrence happens around 1-2 times a month. I am really confused as to what these are and why I am getting them. I have tried to pin-point a certain food I eat or an activity I'm am doing when I get them, but there's nothing standing out to me. Sometimes I get them when I'm warm, sometimes when I'm cold, sometimes after I've eaten, sometimes when I haven't eaten and I'm hungry, sometimes after working out, sometimes while doing school work. Do you have any idea what this could be?