does look like nute problem, but a transplant would help seriously, other than that, could be not enough light to the lower leaves? more than likely its from a nute def of some sort, just re pot it in a big pot and water it with plain water, if after a few days the plant still looks rough(the transplant sometimes freaks them out), give nutes the small amount of soil in your current pot could be causing nute lock-up, so new soil in big pot should balance it out.