Abdominoplasty: 11 weeks post op. Poison coming from opening should I be concerned?

I was advised it could be a stitch or hair but it looks like it's going and poison comes back again. I've been keeping it clean and putting Vaseline on as advised. The rest of my scar has healed well and the hole wasn't there until 8 weeks. It hurts and aches at times. I'm concerned as it keeps coming back even when it looks like it's going to heal. I've looked at it through a magnifying glass and can't see any in growing hairs. Is it something I should be concerned about?