Stop panicking. Even if it was OC, it isn't a rush that early to get diagnosed today. And even if it is OC, the likelihood is that your blood results won't yet be positive as they usually take a while to react after the itching has started.
OC bloodwork is not routinely done. Some areas won't do Bile Acid levels (the best test for OC) unless you have typical itching - worse at night, possibly starting on hands & feet, and severe (e.g. stops you from sleeping, actually wakes you up) - AND you have some sign of jaundice or liver dysfunction, such as elevated LFTs, very yellow urine, yellow whites to your eyes, etc.
Try wearing cotton socks and moisturising your feet tonight in case it's dry skin or normal sweating - if that works, it isn't typical OC itching.
One foot itching a little bit is not typical of OC. If you're really worried, you could ask your MW or GP to run LFTs (Liver FUnction Tests) but they wouldn't be much use TBH - one negative test, especially of LFTs, does not exclude OC and as I mentioned, the blood results typically react some time after symptoms become severe.
I'd wait and see if moisturising & cotton socks stops it and whether it spreads. If it spreads to both feet and your hands/arms and becomes increasingly bothersome, then push to get properly tested.