what kind of soil is she in??
also how much of the 7-3-3 have you been useing? quantities/gallon /week??
have you ph'ed your soil recently? sometimes nutrients can build up and cause lockout becuase the soul gets to hot. if that white widow is not a huge feeder then nutrients added will build up and cause lockouts/ or ph imbalances.
CalMg is only absoutly neccisary if you run a reverse osmosis filtering system. if your on city water there is no real need to add calmg. well/city water can be tested with tds meter when first getting water out of tap to see what your starting baseline is. also if on city water be sure to distill for a few days before useing to get rid of flouride/clorine. yucky stuff
if you need help checking ph let me know.
and fyi i live BFE and order most of my supplies through amazon. works great for me and have access to most prodcuts on the market.
if you dont have one already grab one of these
http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_1?ie=UTF8&qid=1411469248&sr=8-1&keywords=tds meter
also get a ph meter or strips or something to moniter ph weekly at least. for this stage of growth looking for 6.2-6.8. During flower i drop down to 5.8-6.2. (every strain is unique and this is what works for me)
your lady is going to be fine! answer some of these question and well figure it out.