This is difficult to answer without knowing the patient's history. Rheumatoid arthritis is one possible cause of edema in the toes. There are many other diseases or causes ranging from a blunt physical trauma, to athlete's foot. Other causes could be an insect bite or other fungal infection. But given the age of the woman, the fact that she does not have diabetes, and that the pain is not in the big toe (which would indicate gout), the problem is either an infection, or arthritis. Arthritis typically doesn't spread quickly, but develops over time, so this would point towards an infection. If there was a fever, the infection would be bacterial in nature, but probably the woman is suffering from a fungal infection. Fungus can spread by contact, and toenail fungus affects 50% or more of people by age 70. But your description didn't mention discolored nails so this may not necessarily be the case-it could be athlete's foot or another type of fungal infection. If this is a real person, I would highly recommend an evaluation by a medical doctor where a more extensive physical history could be taken.