sick

Question
my guinea pigs is bleed from the bum and makes a different noise, like he is in pain? what do i do

Answer
He may have a urinary tract infection.  He won't get better without antibiotics from the vet.  Until you can get him to the vet, make sure his bedding is super clean as guinea pigs' short legs make them very susceptible to picking up infections from dirty bedding.

Good luck and let me know if I can be of any more help,
~Lauren