Chris and Dwayne at American Graffiti in Brighton (americangraffititattoos.com) do a great job with cover ups. They have both been in the biz for about as long as I've been alive (I'm 28) Outstanding artists. Also Rachael (thier peircer)is certified in Blood borne Pathogens & The Principles of infection Control. She has very extensive knowledge on treatment of both tats and piercings. 810-220-2066.
Also, shoot a message over to Rev Reverence or Oh_My_Goth, both know a plethora of very talented artist that may work out better for you if Brighton is too far away.