We have a separate hot and cold control faucet. The cold water only has a rotten smell when it is turned on. No other faucet in house has this problem. So far I have cleaned aerator. No help. Any suggestions?

We have a separate hot and cold control faucet. The cold water only has a rotten smell when it is turned on. No other faucet in house has this problem. So far I have cleaned aerator. No help. Any suggestions?
Shut the water off at the angle stop and open up the valve, Remove the cartridge and soak it in white vinegar. Now close off the spout and fill the valve body with white vinegar. Let it set for a few hours and reassemble. Smell better now? Let me know, Tom