Blood blisters on nipple rings

I've had my nipples since about October. I know they take forever to heal and they do a lot of weird things. 
Finally my troublesome nipple seemed to calm down. I get in the shower today and I have a huge blood blister on it. My piercer (who has retired from piercing but is still the only person I trust because he went to college and studied certain things to learn more) said to leave it alone and treat it like a new piercing and don't fuck with it. 
Can someone who's had this problem lend me some advice? It's sensitive and I refuse to go to a doctor unless it gets infected (I know the signs) because in most of my cases they don't know shit lol.