Both eyebrow and niebuhr piercing can easily try to work its way out, because in both places bone is so near skin and can push jewelry out.
Best treatment is to wash piercing twice a day with warm water. In these piercings you do not use any antiseptic liquids, it just makes skin dry and may cause the jewelry grow out.
Healing time is usually from 2 to 3 month.
Sometimes bruses can appear near eyebrow or under eye after piercing. This is normal and there's no need to be worried about it.