I got seriously injured so I had to get several stitches.
「大怪我して何針か縫った」は英語で I got seriously injured so I had to get several stitches といえます。
大怪我 = serious injury
何針 = several stitches
simple に言いたければ、
I got several stitches.
だけでもいいです。これをいうと、聞く人は話している人が大怪我したと思います。