租客报怨厨房有臭味，但找不到臭味源头。谁有这方面的经验？

租客说厨房有臭味已经3个星期了，他找遍了厨房各个角落，没发现异常。

For the last 3 weeks, we have stinking smell that is unbearable in the kitchen dining area.

We checked under the stove, fridge and everywhere if it was a dead mouse or something.

哪方面的专业人士能解决这类的问题？还有哪些可能性？谢谢。