I visited my family for Christmas, and my dad smells horrible. What might be wrong?

So, I visited my mom and dad for Christmas. The first thing I noticed was that the house was really hot--like 83 degrees, or something. Dad was complaining about his feet being cold, and that is why he had the heat turned up so high.

Due to the heat, he sweated a lot, and the smell was awful. The stench was like sulfur. I could hardly stand to be near him due to this.

By the way, he is 73, takes medication for high blood pressure and type II diabetes, and is probably 50 pounds or more overweight.

With these facts presented, can anyone give any guesses as to the source of the smell? I said something to him about it, and he brushed off the subject. I am a little worried about this.
I visited my family for Christmas, and my dad smells horrible. What might be wrong?
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