I keep getting these small itchy red dots on my skin. they come and go in different areas, mainly legs, arms and chest. i havent changed anything. they appear and sometimes disappear in minuets. is it heat?

Likely Hives: What you are describing is Hives or medically known as Urticaria. Many times we do not find the cause of this but you need to make a diary of when this occurs, what things you have done, such as new foods eaten, new meds taken, etc... to try to delineate a possible cause. You also need to be seen to be evaluated for other possible causes that may need treatment.

Possible: A condition known as cholinergic urticaria occurs after a rise in core body temperature (cooling off period after exercise, hot shower, stress, sunbathing etc). This is a benign condition which can usually be controlled with antihistamine.

Dermatologist: I recommend an evaluation by a dermatologist and hopefully these lesions will be visible at the time of your skin examination. The spots are too evanescent to be insect bites. They may be variations of hives.

Vasculitis: it could be insect bites, bed bug bites, dry skin, or urticarial vasculitis. Parasitic infestation with scabies and certain medications like Plavix or aspirin can be associated with similar lesions as well. Heavy perspiration and heat can be a cause. it is rare but few disease with deposition in skin can also cause it. It is of note that you only has lesions where you can reach by hand easily.

Check platelet count: If this persists, go to your MD. A logincal test would be complete blood count with platelet count. Low platelets could present with this type of picture, as could recent streptococcus infection.