Unable To Identify Deficiency/Problem

Blueberry w/ PH@6.5 sitting in Fox Farm Ocean Forest Soil for 2 weeks and fert'd w/ Fox Farm Grow Big.

Problem showing up on mid -> larger/older leaves from plant base -> mid sections.

Any Ideas?

How strong are you mixing the nutes? I use the same nutrients and dont have a single problem out of them, I use a mixture of 1 tsp per gallon at the age of your plants but when you start to flower, id go with 2-3 tsp per gallon after you use the nutrients a bit you kinda know how much your plants can handle, but dont worry your plant should be fine man.

Nutes were added in low dosages of 1/4tsp/G only after showing first signs of a problem - problem initially showed on 2 leaves. Have moved up to 1tsp/G, but with no signs of improvement - a total of 5 leaves showing the same signs.

Problem is only affecting 1 plant, but it is the only plant of that strain.