What is wrong with this plant?

This is my first grow. I just threw some seed in cups and put them in an aquarium and they grew. I ended up building a grow box. Its about 2.5 ft * 2.5 ft and about 3 1/2 feet high. I have 3 40 watt 1270 lumen CFL bulbs hanging about 3 to 4 inches above the plant. I have a fan that blows through the box and the temp in there never gets above 80 or so.

This plant looked really good. I went to 12/12 which was about 12 days ago. I started seeing the flowering about 8 days later. Today I came home and the plant looks close to death. I would really like to salvage this if possible. The pics arent great but basically the bottom leaves are all yellow and some are orange and dropping off. Any ideas?

I have a question for you what happens to plants in autumn when the season changes and the light changes to 12/12. LOL It happens during flowering, there are ways to combat it, however I am not schooled on this yet. But some people would say this is normal. My plants looked just like this when they were in a pot that small and were this size. I had some in a closet very similar to urs.

Edit: You plant may also be pot bound and the roots cannot support those leaves because the bud is growing bigger, that is also a possibility.