Out of ideas. High traffic site, low revenue

I have a four year old site in the FIFA niche. In 2011-mid 2013, the site was awesome. There were months I'd make $3,000. At it's worst months, it still managed $1000 or so. At it's best, I was referring sales to two ebooks. I also was able to score a private advertiser or two for a few months out of the year, and that was great.

Then things changed. I tried to branch out and create my own ebooks which did not perform well, and ended up burning a bridge with the creator of one of the ebooks in the process. I closed down my email list that had 15k subscribers over a year ago because Aweber fees were causing me to lose money. I couldn't sell to people. I still can't really. I don't know what it is. I tried Adsense again and got a dismal 0.4% CTR. Recently, one advertiser came back and paid me $1,000 for a month of advertising on a product that was directly relevant to my site. Not a single conversion, and he didn't continue. I tried to refer a very relevant product and its only making me $200-300 a month right now, dominating all of my ad space. Granted, my traffic is a third of what it was at its best, but I'm making 10% of what I used to.

I just feel so beat with this. I don't even know where to begin. Every advertising method just seems shady and like it wouldn't work out for me. BuySellAds did not accept my site.

I'm not here to feel sorry for myself. I want to figure out what's wrong and fix it. That or sell it if I could get enough for it, but I doubt I'd be able to get what that traffic is really worth because of the revenue situation. What can I do?