Hey there,
I don't know anything about the thrush, legs aching etc.
My symptoms were extreme tiredness, thirstyness, itchy feet, memory loss (usually in the morning), dry throat, among other minor symptoms.
Of course, the fact that your sisters sons have diabetes as well as your husband do make it possible, but still very impossible. Still, I remember having thrush on my penis around that age as well, and it turned out to be an ifection I believe, that was sorted easily.
I wish you the best of luck in your sons appointment tomorrow, and let's hope it's something else (although that probably sounds terrible, I'm sorry.
)
Of course, if it is Diabetes, you still have this forum for your suppot, as well as your other family members.. If controlled properly, he can still lead his life as much as anyone else.
Good luck.