A Children in this situation often complain that they are left out and that others talk about them behind their backs, but they lack an understanding of what they need to do about it.
They may have unrealistic expectations coupled with resulting judgements about themselves (for example, "Everyone must love me all the time or I am worthless"). Most people are not aware of their reasons for doing or avoiding things, which can be subtle and habitual since early childhood.
Since your pupil is now missing school more frequently, you should probably ask the education welfare officer to look at ways of re-establishing regular attendance. This will mean direct contact with the home and opportunities for parents to discuss any relevant circumstances.
If you are lucky, this service will be involved in multi-disciplinary work alongside educational psychologists and social workers to provide a range of support and opportunities to meet individual and family needs.
School could provide a daily meet and greet with a member of staff, work with a counsellor to develop her strategies and confidence, or structured in-school groups to provide peer-support.