Muscle soreness on fruit only diet.

Yo,

So I've been on the fruit only diet for at least 2 months, with plenty of fresh OJ, LBB, and kidney + pancreas tincture.

Besides the strength loss and weight loss, and the occasional feeling weaker than normal (compared to the vegetable + meat diet) I noticed my muscles are getting sore from hardly any exercise. The only time I ever had muscle soreness when on the meat diet was after a heavy weightlifting session, or running a marathon.
So why are my muscles sore from hardly any strenuous exercise (just walking around will make my calf muscle sore the next day)?

My mate who is doing a fruit only diet also reports sore muscles, especially lower back.

Edit: I don't do any strenuous exercise anymore because I don't have the energy or power. Will I regain this strength, or is it impossible on this kind of diet?