you have to get a ph test kit. the thing that sticks out is you dont check the ph of your water, all of the problems you are having can come from improper ph. I would also invest in some cannazym(9 bucks at BGH) since your roots are now in a little stunted state as well.

when ph is off, the plant cant absorb nutes or water correctly, so it does what you are describing. As for never having the problem before, not to sure? Mabey you had differant water, or something changed in the city or the ground? or mabey you had a strong strain, that will grow anywhere. Mabey this strain is a not so strong strain for mold and pest, desises etc.