It certainly appears your father has had a severe reaction to a spider bite or has been bitten by a poisonus spider (i.e. recluse or black widdow).
Bacterial infections can be associated with spider bites as spiders carry bacteria on their mandables (fangs).
If the bacterial infection is under control and the bite area is healing and decreasing in size you can control itch, pain, and inflamation symptoms with Bite Rx. Go to: http://medicinalremedies.com/GenProduct?SKU=NativeBite