HELP: Plant not growing and has strange spots

Can someone help please if you have seen similar problem before. The problem started when I replanted to a larger pot, the soil used is like 40% perlite/vermiculite 40% coco and 20%MG premix. Water I used were tap water like ph 7.5+ but it grow fine before I re-pot. I lowered the water ph and gave it some nuts and small spot began to appear on lower leafs (see picture). I cut away the worse parts but these are new patches. The growth of the plant has stop or very very slow indeed since. I have flush it twice and not seems to help.

def a nute problem,dont bother to cut bits away your stressing the plant,check your run off for ph and adjust as needed.wrong ph will cause lock out of nute and so stunt growth,how old are they? takes time for them to recover so be patient

let the soil dry for a few days

The plant grows great when I use just the tap water and no problem, but when I lower the waters ph to like 6.8-7.0 the problem started. First leafs started to curve down a bit and grow stoped. then those small dots start to appear and and expanded to cause the leaf dry up and die. nute are like 1/3 strength. I guess could be the downer solution it does not like, or a disease (don't think it is disease because other plants didn't get it). It is 3.5 weeks old and grow under 6x25w CFL on 20/4 timer.

as slk says let the soil dry for a few days,it does look slightly over watered.what order are you doing your solution?make sure nutes first then ph adjust.1/3 strength nutes seems a bit strong,whats your e.c?if you dont know id cut back to 1/4 strength or lower till the plant seems to like it.if it grows fine with plain water then its down to your nutes,make sure you let your ph adjusted solution sit over nite then recheck e.c and ph values.
good luck.

Turns out it was a disease, could be from the soil it was transplanted to. Watched it a few days and the spots got a lot worse, many more leafs were infected. I spray it with fugicide left it a day or 2 the cut off all the bad leafs , anyone that has the spot on it. This is how it look now but it seems to be much happier and start some grow again. The upside of cutting those leafs are that the little leafs on the bottom now got a lot more lights.

This link here helps a lot.
http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver/leaf/