Sche (pronounced [ʃeː]) was the feminine, third-person, singular, personal pronoun (subject case) in Middle English.
Many other variations are noted in Middle English sources due to difference in spellings and pronunciations. See Francis Henry Stratmann (1891). A Middle-English dictionary. [London]: Oxford University Press. and A Concise Dictionary of Middle English from A.D. 1150 TO 1580, A. L. Mayhew, Walter W. Skeat, Oxford, Clarendon Press, 1888.