Well if more than one and u treat both or multiple at same time that what your going to get. Lockout. .Well, calcium in addition to nitrogen, and maybe a bit of K as well. That suggests to me it is hungry, not single nutrient deficient, or a lock out.
I still want to know if it is surprisingly light when you pick up the pot before you water it. Trying to fix a nutrient issue will be more difficult without good roots.