Dont worry, this does not sound serious. His major problem seems to be lack of sun. As he has been seen by the nurse, there is no real risk.
The red rash in his legs is probably what is termed 'Gravitational Dermatitis'. It is also called by various other names like Stasis Dermatitis, Gravitational Eczema, Stasis Eczema, Venous Eczema, etc..
As we age, our vessels become increasingly fragile and at the same time, there is chronic venous insufficiency which leads to pooling of blood in the feet. As the vessels are fragile, some of the blood leaks out, specially after some provocation like prolonged standing or walking, leading to a itchy rash in the ankles and feet. This clears off after some time by itself, you need not worry about this.
You can wait for his appointment.
Meanwhile take care to see that he has a lot of fluids and does not get dehydrated. Also take care to see that he has a nutritious diet.