Hi,
You have noted these red
patches to occur immediately after showering. How would you describe these
patches? Are they flat or elevated, do they itch? Any associated scaling?
This may be a fungal infection or an allergic reaction. Sometimes, the skin may react to temperatures and this may be true in your case. Extreme hot and cold temperatures may cause red elevated patches or rash on the skin which may spontaneously resolve. However recently, you have noted the presence of itchiness.