If Its Not One Thing..Its Another: Help Diagnosis

Alright...so to begin i had two clones i picked up about a month ago....I have had multiple issues along the way including pH issues (tried using that damn soil tester junk of a device from home depot...it told me the ph was an 8 so i pHed down to about a 6 or so.. when really the pH was a 6.5 meaning I really pH downed to like a 4) .. yellowing leaves...and more recently a thrips infestation. I am an week 2 of thrips recovery - using Neem II once a week for that.


After i figured out it was thrips I thought...great! that explains the slowed grown and the dying leaves near the bottom half of the plant. Well now the leaves are doing something else. I looks like a nut def but i am giving nutes every other watering cycle... and to try and solve the problem i started foliar feeding about 2 weeks ago every 3 days with diluted nutes. Now I'm seeing this weird white "skin" type on the base of the stem nearest the soil. i rubbed my nail across it and it came right off...the stem is sturdy as ever and hard so..im wondering if there is an underlying issue I'm not seeing thats causing the leaves to turn the golden yellow. - attached are some photos and ANY help or suggestions are greatly appreciated

4 200w CFL
Roots Organics Soil
Nutes - Roots Organic: Buddha Grow

Pull dead leafs off ,
when your pots dry up ,,
run ph water6.5 , flush your plant untill the run off is 6.5
then let it sit for a few days , then test your nute water befor you water ,
Nutes drop ph sometimes down as much as 4.0
so test befor you water So
Plain water ph 6.5 water untill the run off is 6.5
then let dry , mix up a your nutes with water ,and your neem oil , ph it at 6.5 (water,nutes,neem)feed
then watch new growth to see what's going on
thumbs

looks just like the C99 pheno i use to have, i swear to god, as soon as that plant consumed all the medium, it started lookin sickly, nothing i could do to fix it...i would try ecips suggestion first, if it dont help, repot

it sort of looks like a defiency, but if your giving it nutrients, micro and grow there shouldnt be a problem, it could also be nutrient burn as some of the leaves do look burned at the tips, best of luck, i would personally water without nutes for a few days and see what happens

its a mobile deficiency... probably mg def

much appreciated! i was unsure if I should flush because it causes more stress - should I continue foliar feeding with nutes? and also is there any worries with the stem turning white? the growth has been so slow lately but I think that was caused by the thrips - never knew it would be so much work trying to get perfect growing plants!