Grey tabby cat with blue collar

I lost my grey tabby cat yesterday around 3pm near the Brighton Palace Pier along Madeira Drive. She's a medium-sized indoor-outdoor cat, grey with a white chest, and she wears a blue collar with a tiny silver bell. There’s a small notch in her right ear and a faint white patch on her left hind paw, which are pretty distinctive. She vanished after a loud shout from a street performer near the West Street entrance and I’ve been scanning the seafront and The Lanes since. I’m really worried—she has medical needs and means the world to me to bring her home.