What is Going on in my Garden?!?

[Tuggie]

I'm having a major problem in my vegetable garden, most my plants have developed dark green spots and are dieing. I thought it might be to cold (live near Chicago) but my broccoli has developed it. My onions have these weird brown spots that are starting to hollow. The cilantro and parsley are actually turning dark green and then red. I'm not sure what is going on. Please help