He should get an exam from his regular MD or a urologist, or both. Kidney stones should be ruled out (if the medication he was given to break them up and pass them through the urine didn't work, he still has them) and also some kind of torsion. Good luck to him.
If the ustilago is in fact used in homeopathic form there's no active ingredients in it. It's either a placebo or it works by energetics, depending on who you want to believe. If the ustilago is some other form, I wouldn't understand using it, as it's a corn disease, so I'm going to guess a homeopath would be using a homeopathic remedy, which is a dilution that is so diluted there's nothing but the energy of the original item left in it. Your friend should, of course, as recommended above, stop using it, as it not only clearly hasn't worked but if that's the only problem your friend had it didn't need any treatment to begin with. As to the pain, if he has kidney stones, they hurt, and they can hurt all over.
So first, "nightfall" is a completely natural and normal thing to happen. It's called nocturnal emission, and are not harmful to you.
I think your friend needs to see a medical doctor - not a homeopathic one - and get an exam. If he is still taking the ustilago maydis, he should stop. What he's experiencing may be a side effect of it.