I have an allergy and with eliminating probable causes, doctor narrowed down to 2. Doctor said allergic contact dermatitis and that it has started to spread locally on other parts of my body. I have stopped all contacts with both materials and have been prescribed antihistamine and lotions. Even after taking the tablet, I feel itchy all over.  1. Does the itching stop after few days of dosage or does it stop immediately?  2. How do we find the root cause in case it was missed?