Funny, but we had a thread on this exact topic a few days ago.
The
serial comma after B here - A, B, and C - is known in the UK as the
Oxford comma. It was favoured by the Oxford University Press - but not many others in BE.
It is known in the US as the
Harvard comma.
A web search for any of those terms will find lots more information.
So it is correct, if your editor accepts it, to write:
... a wide range of medical problems, including infections, aches, and pains.
If you were to insist that "aches and pains" represents a fixed entity, an inseparable pair, then you can't just leave the comma out. You would have to insert another and. Trying that without the Oxford comma:
... a wide range of medical problems, including infections and aches and pains.
That's not good, so try inserting the comma:
... a wide range of medical problems, including infections, and aches and pains.
Better, but that clunky phrase with two ands still bothers me. I'll have to reverse the order and keep that comma:
... a wide range of medical problems, including aches and pains, and infections.
Found the thread:
Comma and And