All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If Jeddah is not your place of residence and you wanted to go there for a need after Hajj before you perform the farewell Tawaaf and then come back to Makkah for the farewell Tawaaf, then it appears that you are not sinful for doing so and you are not required to do anything although it is better for you not to go out of Makkah before performing the farewell Tawaaf.
Shaykh Ibn ‘Uthaymeen was asked about a person who goes to Jeddah before performing the farewell Tawaaf while having the intention of coming back to Makkah, and he is not a resident of Jeddah, and he answered: "If he is not a resident of Jeddah and he just went there for a need while having the intention to come back to Makkah and perform the farewell Tawaaf, and then leave for the place (or country) where he resides, then he is not sinful and he is not required to do anything."
Allaah Knows best.