climb out of the sandbox

This is my first post here and I wanna thank you all for the great advice I've been reading during the past weeks in this forum. Seems like this is a place for winners to be.

I've been seriously working on 3 websites since the start of the year now. I monetize them through a combination of Amazon and Clickbank. Adsense has bought in such pitiful amounts that I don't bother so much with it.

Right now, only one of these sites is doing well so I'm going to follow the advice of many here as a relative newb and concentrate on only one until it succeeds.

For info, my sites are niches, they are what I know and enjoy writing about and and with needs associated with them:

- alcohol & drugs
- music & becoming a DJ
- libido health

My problem is that according to all indications, Google has sandboxed 2 of these sites! It's actually the second time they've sandboxed the DJ site. My traffic from Google is almost non-existent and I basically depend on other resources.

I'm confident I'm doing everything right but very frustrated that 2 of these 3 sites (with around 100 pages each of good niche content) seem to slip right down and onto page 8 of the search engines after nearly reaching page 1 every time I get there! I feel like I'm spinning my wheels.

So far I've checked all the guidelines for not being sandboxed. I've built backlinks and some good content (people tell me it is).

Has anyone been sandboxed before and what did you do about it?

Any advice would be much appreciated. Maybe I'll get an idea of what is really going on.