Ring worm is a fungal or yeast infection, its not actually a "worm", just in case you were worried. HW does not cause fungal infections, nor does contact with animals.
Yeast overgrowth comes from too much sugar in the diet, use of antibiotics, and contact with moulds in the environment. If it is a fungal (yeast) infection, the humaworm may be pushing your infection up to the skin surface because HM has anti fungal properties in it as well. It may simply be a rash, which is a good thing, meaning the HW is working.
If it is "ring worm" in a ring formation, a yeast infection in other words, you may have an infection, and you may need to take further action in addition to the HW. Having said that, the HW may clear it up on its own given its anti funal properties. Given you have had this happen, I suggest visiting the candida forums as it may be likely you have an internal candida infection which needs some dietary changes and treatment as well. Topical creams such as lamisil, or internal tablets such as diflucan also work ok if you want do attack this quickly, but you can also work on this with natural means. The candida forums have loads of information.
Just make sure it is ring worm (candida) and not just a rash. Rash is very common with HW and it means it is working!! Worms, candida usually do go hand in hand and occur simultaneously.