I first had my ears pieced with a gun, 30 years ago, as a child. I stopped wearing earrings for a few years, and in 2006 found I could no longer easily get them back in.
So I got them re-pierced (gun again) about 2mms from the original site. Whilst they healed well, I started having problems with irritation.
I stopped wearing earrings for 9 months, then couldn't get them in at all.
I went to a tattoo/piercing parlour about 3 months ago. The piercer tried, but failed, to get earrings in the holes, so he re-pierced over the site of my first piercing, with a needle & titanium stud things (longer than studs, with a screw on ball).
They both seemed to heal nicely. My right ear has no problems. I stopped the sea salt washes at 8 weeks, and can take the earring out - no problems.
My left ear though - is another story! My toddler did use to catch it a lot, and it would bleed. I carried on the salt washes, it would get better. Then one day it was weeping. I carried on cleaning, so the piercer, who said they were fine, and he was impressed how well they'd healed - fine.
Then the unused hole started swelling up, and when cleaning the piercing it would burst when touched. I noticed that at the same time I started getting pus from the piercing.
I've been back to see the piercer, who said that I hadn't looked after it properly 
even though 4 weeks ago it was healed.
It keeps happening though - the piecing is fine, nice & clean, but then the unused hole will swell up, burst with pus, and then the piecing gets manky.
I've asked whether the old piercing and the new one could be connected inside - maybe it ripped when DD pulled it, causing a space for gunk to collect (they are only 2 mms apart), but apparently this couldn't happen. He couldn't explain why the old one affects the new one.
I'm at a loss - any advice?