Infection?

I've had my nipples pierced for almost 3 months now and two weeks or so ago I started getting this yellowish crusty stuff on my bars from where the nipple's been pierced. I clean them once, someone's twice a day and sometimes it'll be a few days before the yellow stuff comes back sometimes it'll come back sooner. Is this a normal part of the healing process? Cause I know they take six months to completely heal. Or is this a sign of a possible infection? Thank you in advance!