What Causes Enlarged Lacrimal Gland In Right Side Causing Painful And Itchy Eye?

About 2months ago I felt like I had a foreign object in my eye. Then it started being painful all the time. I went to see an eye specialist and he got me to go and have a MRI scan which showed that I have an enlarged lacrimal gland on the right side. I have to see him again in a month s time. What could be the cause of this and do I need to worry? At the moment it is painful and a bit itchy also swollen feeling but not so much when I look at myself in the mirror.