How long did you run the keto diet for? It takes a week or two to burn up all the carb-based energy available in your body (glycogen) and then transition over to using ketones. You have to get thru that transition to continue. I would caveat that on a keto diet you can't expect to have any "burst" energy - e.g. if you want to do HIIT cardio or super sets. Its just not going to work like that because you don't have the quickly available energy source. If you stick to slower paced training (e.g. walking cardio), generally you are ok. But also you need to adjust your training expectations to what a cutting diet can support. If you're not eating big you can't lift big. That said, I've done some very solid training while on a keto diet during competition prep.
RE: a carb rotation, I would suggest you do more research yourself and check here for some good basic stuff on getting your baseline numbers:
http://www.ironmagazineforums.com/new-members-begin-here/97077-read-me-first-homework-1-newbies.html
Just doing some back of the envelope numbers, if you're ~200 lb, guidance is to eat 1.5-2 x your weight in protein grams / day (to maintain or grow) and 15-20 x your weight in total cals. I would for a cutter, take 3000-3500 cals as your base cals with say 300 g of protein per day, split equally across all of your meals. Then the remaining calories to make up the 3000-3500, split as a sliding ratio of calories from carbs to fats over the 3-4 day cycle, while keeping the total cals the same. E.g. (I'm just making up these numbers, but to illustrate)
Day 1: "high carb"
300 g protein
300 g carb
10 g fat
Day 2: Med Carb"
300 g protein
200 g carb
30 g fat
Day 3: "low carb"
300 g protein
100 g carb
50 g fat
Day 4 = Day 1, repeat
So you get the idea - high carb day means high carbs, low fats, constant protein cals. Med carb day means lower carbs, higher fats, low carb day means low to no carbs, replace all those cals w/ fat cals. You can pick the length of cycle and degree of change within cycle. A more aggressive cycle might be high carb day = 300 g carb, med carb = 150 g. carb, low day = zero carbs.
Another note - when we talk about carb cals, we're specifically referring to non-fibrous or starchy carbs such as oats, rice, etc. We're not really counting carbs from veggies. But either way, the first 1-2 times you go thru the low carb day, you'll feel it - the lethergy, maybe moodiness, etc. But once you've gone thru it you know how it feels and can better manage it.
Another way to do it is keep the say idea of high / med / low carb days, but match them to your heavy or light training days instead of just sequentially doing them and having say a heavy leg day happen to land on a low carb day. Depends. I've done both. I personally like the sequencing and just deal w/ whatever training day happens to land on low-carb day.
