I have had pretty bad ringworm over the years and still do have it some. The candida diet can very much help cure ringworm. I have also had really bad hair loss, and after doing the candida diet for 4 months, my hair has grown back! At the least, I would recommend trying the diet for 2 weeks to see whether you have any improvement.
As far as gaining weight, it will be very hard to do while on the candida diet. However, if you eat a ton of food with every meal, I think that it is very possible. One guy on here ate 6 meals a day and was an athlete, so with this in mind…you can eat 6 meals a day and probably gain weight.
Most people lose weight on the diet because they were slightly/quite overweight to begin with. I personally lost 10-20 pounds; I am 6ft tall and used to weight 165pds. Now I am at or near 140. So I was a pretty skinny guy to start with but still lost weight. Hope this helps.
Good luck with the diet!