Well as you describe she needs to be seen by dermatologist /Vascular specialsit for a clinical examination to rule out underlying possible causes like Hives, Vasculitis - (inflammation of the small blood vessels of the skin), Peripheral vascular disease,venous insufficiency,Dermatitis.
It can be medication induced adverse effects as some blood pressure medications dilate the peripheral and cutaneous vessels of the body to reducce the blood pressure, the dilatation of the arteries and veins supplying the skin causes more blood to pool in the skin especially when the patient is sleeping or immobile for a long time and thus, causes the redness which is without an itch and swelling.
Thyroid function test, CBC, ESR, Absolute Eosinophil count, Color Doppler study should be advised.
I hope this helps.
If you have any further query then feel free to ask.
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This is great information, more than what we had, thank you so much for your time and expertise.