What Causes Itchy Red Dots On Scalp?

Hi a couple of days ago I got these red dry dots on my scalp and they are very itchy and flaky. I started using this shampoo for psoriasis but it is not going away.. Instead it is spreading all over my face and body. I have gone to the walk in doctor and she prescribed me some antibiotics but said she didn t know what it was. So far it s getting worse not better. What could it be ?