Getting back after several months off diet

I had been on slow carb for 4 months about a year ago and bulked up a lot at the shoulders, ate additional protein and exercised every 4 days. Results were stunning. Because of several reasons mostly because of business I had to get off the slow carb diet and ate whatever came in my way. Now weighting about 20 lb more than I want and muscles need urgent build up. I had a check up at the hospital indicating some kidney problems, very minor but doctors suggested that I should leave off the extra protein as it is putting a strain on the protein. I stopped taking my 2 protein pills a day and kidney functions improved.

Now I want to get back on slow carb diet. I want to loose 20 lb and build up the body as good but also as healthy as possible.

any recommendations?