It is highly contagious. Use a new towel when showering everyday, wash clothes and avoid holding them against your body during transfer, wash hands and under nails often. Lysol and clean all laundry baskets, shower rugs, etc. I'd clean the laundry machine too, all surfaces that clothes touch going in and out. Also, any common surfaces in the house...... couches, lightswitches, etc. Once you decide to do battle, make sure you erradicate it once and for all.
When we were kids, we picked it up from sandboxes and playing in dirt. (leading me to believe it is related to animal feces). If she's a gardener, that might be the culprit.
I did see a ringworm remedy at Walgreens the other day, just by chance. it was by the Lice removal kits, lol.
Here's a link to Mayoclinic, all you need to know.
Sounds like a can of tinactin and cleaning up any possible infected area's of the house is the way to win the battle.
http://www.mayoclinic.com/health/rin...-home-remedies