Infected ear piercings.

My daughter had her ears pierced over two months ago. We had no problems the first six weeks and decided to change them after six weeks. One ear got infected and I assumed it was from putting in cheap earings. It's been weeks of ear infections one ear then the other back and forth. I've put alcohol and neosporin on them.  Am I doing something wrong?  I put the peiercing studs back in after he first infection and have left them. I just don't know what to do anymore. I feel so bad for her.  I just don't understand how we went the first six weeks without a single issue to this. Any insight is appreciated.