I would strongly recommend that you go to see your primary care doctor
about this issue as soon as possible. There are several different potential causes of red, swollen feet, and most of them are serious and require treatment.
For example, redness and swelling in the feet may be a sign of a skin infection. If not treated with antibiotics, a skin infection could continue to spread and require hospitalization.
Red, swollen feet may also be a sign of a blood clot in the large veins in the leg, called a deep venous thrombosis. This can be caused by immobility or inactivity, and it is also associated with various other chronic medical problems. A blood clot would need to be detected because it can put you at risk for the clot breaking off and traveling to the lungs.
Swelling in the legs or feet can also be a sign of trouble with the heart. When the heart does not pump properly, some of this liquid may back up into the feet, and the swelling can lead to soreness or redness of the overlying skin.
Start by getting in for an evaluation with your primary care doctor as soon as you possibly can!