Does anyone have any idea

[Awwlookatmybabyspider]

What this could be on my face.
I remember last night getting itchy, but Didn’t really think much of it. Then this rash or whatever it is appeared on my face.
I cleanse tone moisturise twice daily. Clean my make up brushes/sponges once a week.
I have started using a new foundation, though. Could it be an allergic reaction, but Surely it wouldn’t be localised to just one side of my face.
Thanks in advance for any thoughts and advice

It looks like you might have been bitten by something. Especially as you say it was suddenly itchy.

I'd stop the foundation and put germolene or similar on that patch rather than your normal moisturiser for a couple of days and see what happens.

It looks like an allergic reaction especially as it was itchy. Could be anything, new washing powder for example or shampoo. Don’t put anything on your face, just wash with water.
If you have more swelling, or it spreads, feel in any way unwell you must go to hospital,

Germolene would be safe, PP is right.
This is great for insect bites www.boots.com/anthisan-bite-and-sting-cream-20g-10016491

Heat rash? Can you get some old style piriton in case it’s an allergic reaction?