I don't know anything else about OCD but I ran across this in a book I am reading:
"A study by J. Yaryura-Tobias M.D., established that trytophan combined with niacin and vitamin B6 stabilized compulsive/obsessive patients in six months by increasing the availability of serotonin, the brain's calming newotransmitter. I suspect Dr. Yaryra-Tobias' study would have produced results earlier if he had combined his regimen with inostol. An Israeli study recently appearing in American Journal of Psychiatry reports that this B vitamin effectively eliminates symptoms of compulsive obsessive disorder over a six-week period and, unlike accepted drug treatments, has absolutely no side effects. It works by regulating the action of serotonin within the nerve cells."
The title of the book is "Seven Weeks to Sobriety" by Joan Mathews Larson, Ph.D. I bought the book because her breakdown of the symptoms produced by specific vitamin deficiences is excellent.
I think that I have heard that candida depletes our vitamins Bs, so by treating both the candida and the vitamin deficiency would seem to make sense. I think it would be helpful for you if you could track down this research.