YOU SAID:

Opens his mouth but the vomit won’t come out

INTO JAPANESE

口を開くが嘔吐物が出てこない

BACK INTO ENGLISH

I open my mouth, but I don't get vomit.

INTO JAPANESE

口は開くが、嘔吐はしない。

BACK INTO ENGLISH

The mouth opens, but does not vomit.

INTO JAPANESE

口は開くが、嘔吐しない。

BACK INTO ENGLISH

The mouth opens, but does not vomit.