What Causes Recurring Rashes On Forearms And Stomach?

Hi,my name is Sanjiv.I am 32 years old.My height is 5.8",and i weigh 72 Kgs.
Everyday evening from 4 pm to 6 pm,I get rashes on my fore arms and stomach.This is only at the mentioned time,but rest of the time I will be normal.For this if I take CETZINE tablet,the rashes will reduce and also itching too.
My health is normal and I don't have any bad symptoms even in my past.
I smoke 4 cigarettes per day.Whether the rashes are coming for this?