If you are reading hi ketosis, that usually means you are dehydrated. I could be wrong. If you are following the protocol and not cheating, then where is the sodium coming from? Are you salting your foods? If so, stop. Salt retains water.
I don't promote apple days, altho, in your case, with hi-ketosis, it may help. From my experience as with others, apple days are good for one day only and usually the weight is back up the day after the apple day.
Not sure of the foods you are eating, maybe increase your protein intake by 1/2-1 oz at a meal. Eat only one fruit. Replace it with a protein shake (EAS or Jay Robb).
If you are using table salt (the cheap stuff at the stores with iodine in it), I would stop using it. That is not true (or real) salt and can be harmful. GS had mentioned it in one of the journals about how bad the stuff is. If you MUST salt, use celtic or hymilayian salt. These will contain natural minerals that are good for you. But, use it sparingly. On the hcg diet, salt can be your enemy. Trade off with seasoning and spices. Watch out for "blends", many contain salt.
If your are working out, you body may be retaining water to repair muscles. This is normal. If your weight goes up every so often, I wouldn't get too worried over it. As long as the weight loss in generally going DOWN. If your weight stalls out for over 6 days, then something needs to be changed.
Apple days are only if your weight has stalled for 5 days or longer.
I hope this helps.