This all sounds about right to me. After so long of punishing your system, it fights you back a little while getting healthy again. I would suggest getting a multi-vitamin, and considering the amount of water you're drinking, some sports drinks as well to replenish electrolytes. Long, hot, epsom salts baths can help pull toxins out of the system and soothe muscles to help relax and sleep.
12 days is great... ride it out and the cobwebs will clear, and you'll be feeling physically much better soon
