Crosstalk between Ethernet and Analog Signals on PCB
A signal with less than 10 ohms impedance will be susceptible to magnetic mode interference, and although the Ethernet pair will not radiate much common mode energy, there will still be some, and most of this energy is magnetic mode. See this previous question and answer for more details on common mode radiation, the causes and some solutions.

Apart from separating the analogue signal by some distance (which is an effective method of reducing interference), it may be necessary to add a guard track between the Ethernet pair and the analogue signal (which could probably be considered DC relative to the Ethernet pair). See this excellent article for guidance on guard traces.

That is just the starting point. Do you have any simulation tools available? Some permit proper simulation for both pre- and post-layout; if you have such tool(s) available, I strongly suggest using them.

HTH