I don't know what the 'spot' is, but looking at the roots, I would tend to think it's a culture issue. Possibly keeping it too wet in the old mix. (The roots don't look so good in the pic.) I see in another post you just mounted this, so I would just water daily and wait for new roots to come out. Good luck!
I use Essential brand rooting hormones to accelerate root growth. The main ingredient for root growth in the product is gibberelic acid, a strong hormone, that does not burn plants if used too strong.
were could i get that? do i need that? i was wondering if there was something im doing wrong to make the roots not like that and anyway to change it without using hormones. would a fert be of help? and what kind of fert. and how to apply that fert?