I feel itchy all over on a cloudy day.

According to your description, it is cholinergic measles.

Your illness is caused by the accumulation of toxins in your body. Toxins can't dissipate in your body, can't penetrate outside and are suppressed in your skin. The ultimate cause of chronic diseases is that patients are eager for success and blindly use drugs, which eventually leads to repeated attacks. Personally, I suggest not to drink, eat spicy food, drink more water, eat more fruits and persevere on the premise of improving your own immune resistance.