Thanks for writing to us.
From the description i seems you are having chronic urticaria
. In most of the cases no cause is seen but in few there could be association of autoimmune diseases, thyroid
disorders, rheumatoid arthritis
with the same. Sometimes hot or cold weather, pressure, water, sunlight, sweating etc too can induce urticarial lesions. So basically a proper workup and clinical history is required for accurate diagnosis and treatment.
Just to allay your doubt its not HIV or cancer.
Hope that helped.