I do itchy all over my body after bath or before...

Causes and treatment of itching after bath
Usually there are several reasons for the mentioned problem, the most important of which is erythrocytosis of polycythemia rubr vera, wich is usually the result of hyperactivity of the bone marrow, which produces large quantities of blood cells as a result of many stimuli, and it is important to complete the medical evaluation through the medical presentation to the
Hematologist to identify the triggers and work on treating them.
Treatments may be for symptoms such as taking some aspirin to relieve congestion and headache and other symptoms in addition to taking paroxetine or fluoxetine to relieve itching. It may also be advised to draw some blood out and also take hydroxyurea to reduce blood production from the marrow, ruxolitinib may also be prescribed For people who did not respond to the previous.
It is advised to avoid smoking, exercise, avoid places with few oxygen, such as heights, and stay away from heat fluctuations.
Medical diagnosis:
Medical diagnosis is made through presentation, evaluation, and completion of the necessary tests, including blood work tests to identify hemoglobin levels, in addition to evaluate erythropoietin levels . A bone marrow sample may also be taken.
Accompanying symptoms:
For some people, there are no symptoms, but some may experience the following:
• Itching and people may notice that it is more after a warm shower
• numbness
• Weakness in the hands or feet
Feeling full quickly
• Excessive bleeding
• joint pain
•    shortness of breath
•    Other
the reasons :
The reasons differ in reality, and they may be due to a primary defect in the marrow or be the result of other reasons, such as weak heart muscles, problems with the lungs, kidney problems, smoking and others.
Advice :
Medical presentation to a hematologist for evaluation and treatment.