Where does “schewynge” come from?

schewynge (Middle English) comes from Old English sċēawung, from Old English -ung, from Proto-Germanic -ungō — -ing, -ion. "Forms gerund nouns from verbs.".

Ancestry of “schewynge”, step by step

Step	Language	Word	Meaning
1	Old English	sċēawung	inspection, contemplation; a showing, spectacle,...
2	Old English	-ung	forming nouns from verbs, denoting verbal action...
3	Proto-Germanic	-ungō	-ing, -ion. "Forms gerund nouns from verbs."

Every word from Proto-Germanic -ungō →

schewynge — Etymology, Origin & Word History | Etymology Explorer