Help! I can't figure this out and the books aren't much help

I need plenty of advice as to what I should do. I don't have pics so I'll have to layout the story. I had a leafhopper problem that was doing a lot of damage to my lower plant so I used neem oil. Worked, but I was under the impression that it burned my plants. The leafhopers are gone but the "burn" would appear to not really be a burn, but a nutrient/soil issue. The bottom leaves are yellowing and falling off. It'snot nitrogen, I've taken care of many a N problems. First the leaves begin to yellow and quickly form necrotic patches in random spots on the leaf and down the center vein areas. The veins remain very slightly green, but not much and not on all leaves. Some leaves curl at only the tip, but not all. The necrotic patches are brwn/red. The problem has now made its way up to the tops of 4 plants (only in a 5' x 5' patch). Other plants seem to be lightly affected to not affected at all. Also, green part of the leaves seem knd of blotchy. This has partially fit into several different nute deficiencies. I'll get to the point, I can't Identify this problem and it may kill my plants. I used the existng soil + some MG potting soil and extra perlite along with slow release plant food for the growing medium. I've never hadthis problem before, but think it may be too much slow release food that's causing possibly a ph problem or nutrient lockup/both. If this is the problem I can't flush out slow release nutes, any suggestions? I've decided that foliar feeding may be neccessary if it can't get nutes from the soil and will be testing ph tomorrow. I really need suggestions, I'm just spinning a big wheel now. It will kill most of my best females which I have a very strong emotional attchement to, lol. But seriously, this friggin' sucks!