Dr?? Please Help Me.. My Baby is sick I think??

Hello everyone!
First off I would like to say thanks to all the people who help with this.. you are true awesome people!
This is my first post.. I would like to say hello to the community as well, I don't any of you but I'm sure I would love you all in real life... We all have one thing in common that's for sure... :)

Ok, here is my problem.. my plant is about 1.5 months old... It is in budding stage, very dark green leaves and very fat leaves.. It is 4ft tall right now... I will post pics when my phone charges ( I have to run out to the car and get it)..

So anyway.. everything was looking great, then all of a sudden I see this one big white spot on a leaf.. just a bit smaller then a dime size.. now that spot is started on the other side of the same leaf and it looks like they are getting bigger and will meet each other and sever half of the leaf off...Plus some leaves are drying up as well the fertilizer felt damp/moist but I added a bit more water just encase..

I am using 10-15-10 miracle grow self water realising fertilizer and I have 20-20-20 all purpose food to add to my water (I haven't used to much of, maybe a couple times).. I have done reading up (tried too anyway) and some say bugs (I have checked and looks good I think) and my house is really, really clean so.. I'm leaning towards maybe not enough N?? what would y'all suggest?
I have CFL lights and they have been doing great for me.. the plant is in a 2 foot by 2.5 foot and 6 ft high wash room cupboard thing with doors (im kind of getting worried the plant wont stop growing).. it is white and very good for my one baby (had two but I had to put one down because he was a boy, was a very hard thing for me to do but I did it and now down to one baby gril.. The way she looks now, I see no problem with lighting issues because it looks big and healthy and the little baby buds are growing pretty nice on it (I am a noob though and this is my first, but have done my research).. I know you all need pics and I will post them later this evening, I have to go out for a bit right now.. But I am worried about her and very scared she might pass away on me and I don't know how I will feel if that happens.. I love her to death and talk to her everyday, give her music to listen too and I know she loves me too and gonna give me a big surprise! even if she doesn't give me a big surprise I still love her and don't want her to die on me!! :(
I need help though, I'm afraid for her life and could really use some help!!
Thanks soooo much everyone.. Oh and the temp the plant is in is around 70 - 80 degrees, sometimes a bit warmer if I have a bath or shower..
Thanks again for any help or suggestions..