Extra fields are grouped so they can be assigned to one or more categories. If you need different sets of extra fields displayed in your content, assign your content to different categories and additionally create sets of extra fields and assign them accordingly to the these categories.
If you wish to display extra fields separately, you can use this feature added in K2 v2.6.2
getk2.org/blog/1068-k2-v262-now-available (use the extra field alias to directly call an extra field name or value). You can place these PHP calls anywhere in your item.php sub-template in K2.
You probably don't need a plugin to achieve the output you want. ;)