For the last year or two about twice a week I'll get an itch somewhere on my chest or arms. My skin appears normal where the itch is. However, when I scratch a single small red bump forms. Then after about 30 mins the itching stops, the bump disappears and leaves a small light brown discoloration on the skin where it used to be.
I do not think these are bug bites because I get them anywhere (vacation, my house, the office, etc...). Also, I have had mosquito and flea bites before and they last much longer than 30 mins.
An advice on what this could be?