It might be something that we call a mucocele
. If there is no pain or redness
associated with the swelling then its more likely to be non infective. Cephalexin
will not help as its an antibiotic and has no role as such.
Surgical excision in the form of a DCR is the only solution to this problem. It would be better to consult an eye specialist who would be able to help you out.
Hope this helps