Strange, possible heat rash on my foot?!

I was sitting out in the sun for quite a while yesterday and when it started to cloud over I sat there for a bit longer but then came in but while I was still out there I noticed the top of my foot from my ankle to my toes was getting quite itchy!. I'd scratched it a few times but didn't ake muh notice of it!. After coming inside, I noticed that it had started to go very red and rash-like (not raised, the skin is still smooth)!. It isn't sunburn because I had been putting sun cream on, and also I'm not burnt anywhere else!.
Since getting up this morning, it has gradually becoe unbearable to touch because it really hurts and still feels fairly itchy!. I have been applying E45 itch cream!.
When I walk now it feels like the part where the rash is "wobbles", almost like there's jelly under the skin!.
Any ideas on what it might be!?
Thanks!.Www@Answer-Health@Com

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