I would call your gi, and see if you can get in with a nurse for the loading dose instead of waiting until october.
I've been on humira for 6 months now, and usually don't premedicate myself, but i do put an ice pack on the site for about 10 minutes before my husband does the injection. (Yes, I'm too chicken to do it, and he's my hero!) Sometimes the injection site gets pretty swollen, and then I will take tylenol and benedryl along with icing it for about a day until it subsides.
BTW- what is the c-diff test? I never heard of it, and as far as I know, i didn't have it before starting humira
Good luck and Good health!