I'm SO glad you have him up to date on vaccinations since groundhogs do carry rabies ( http://www.cfainc.org/articles/rabies.html ).
The heat being generated and the reaction of your companion (skittish) is troublesome. There is probably a bacterial infection brewing. You've done the right thing using the hydrogen peroxide, but again, when a wound generates heat as you describe, it warrants an urgent vet intervention and probably antibiotic treatment.
You've been an excellent caregiver for him and again, I'm very glad to hear he's had his rabies shots. Please take him to his vet or an emergency clinic tonight for this, just to be sure it doesn't get much worse and more complicated to deal with as the hours pass.
God bless!
Many have forgotten this truth, but you must not forget it.
You remain responsible, forever, for what you have tamed.