Dinner is still many hours away [it is 10:12AM]. However, it is FIL's night to 'cook'

Send fish! Hey, I might even give the squirrel a try!
Seriously now, I am a little worried about him

He has had a non painful, swollen foot, ankle and lower leg for a few days now and will not go to the Doctor. I am suspicious of kidney or liver issues and concerned that he is not drinking enough water in this heat .. he has an Iced Coffee for breakfast, a beer at lunch time and starts drinking wine at around 4PM. I very rarely see him drink water.
He is very set in his ways and stubborn [which he allowed to be at his age

] and even suggesting he drinks water or goes to a doctor for a blood test etc is asking for a lecture or tantrum.
I am worried but not sure there is much I can do