5 year old pug with red lump in ear

We found this lump in his ear about a week ago and it wasn't too red at all. But we noticed it again today and it seems to be bleeding and weeping quite a bit. He seems a little uncomfortable when we were trying to clean it and are unsure what it could be 

Hello and thankyou for sharing this case.  Could it be cancer?  Yes, it could.  There are other possibilities; a usually benign tumour called a histiocytoma which may disappear; an inflammatory lesion eg a bite that has become extremely inflamed (uncomfortable place for that); a small haematoma; a foreign body buried beneath the skin eg a grass seed.  It is difficult to tell from the surface, perhaps even for your vet, and it may be in an unconfortable place leading to the possibility of secondary yeast infections etc.  It's definitely worth making an appointment.

Your vet will help you to come up with a plan for identification and, if necessary, treatment.