Kiwomya, appointed in February, has overseen the Magpies' worst-ever start to a season with the club rooted to the bottom of the Sky Bet League One table with only point from their first seven matches.
The former Ipswich and Arsenal striker knows results must improve if he is to remain in his job.
"I don't know if my future is secure," Kiwomya told the Nottingham Post.
"I can't be at the bottom of the table and say that. I've got to try to get this first win on Saturday against Tranmere; and if we can get that we can get a bit of confidence back."