How do I know if it's eczema and if yes, what should I put on it? Should he see a doctor?

If you suspect that it may be eczema, it is important to consult a doctor for a proper evaluation. They will be able to diagnose the condition and recommend the appropriate treatment. In the meantime, it is recommended to moisturize the skin regularly with fragrance-free moisturizers, avoid harsh soaps, and protect the skin from extreme weather conditions. If the symptoms persist or worsen, a medical professional should be consulted for further assistance.