Scalp psoriasis- possible infection? Please help

Hello everyone, I hope you are all as well as can be. I am new to this site and come with a whole giant bag of luggage which I've mostly been able to scrape by without seeking help but now I'm really quite worried and need help from people who have personal first hand experience. Ok a brief summary of my existence so far. I was born more or less head to toe with what was diagnosed as eczema, by toddler age I was mostly clear apart from the whole of the back of my scalp which I have only recently figured is actually psoriasis. In 2008 I was 24 when diagnosed with thyroid cancer and so removal blah blah but the thyroxine leaves me with very dry skin which has worsened my scalp. Getting on with life skip to 2016 when I was diagnosed with low grade brain tumour in my 4th ventricle. On watch and wait, it nearly fills the ventricle and now I've been waking up with an instant headache, the right side of my head hurts, my right eye hurts, right side of the back of my neck too when I felt a small bean size lymph node and when I push it the pain shoots through my head. I have literally just read the symptoms that come with that lump relate to a skin infection caused by psoriasis!! So, can anyone who has had a scalp infection confirm the same? There is no weeping of the psoriasis just so so itchy its driving me mad and the headache is quite thumpy and constant, the electrifying shooting pains are quite unbearable at times and my right side back of my neck is very achy. Is this infection? I've always just coped with it, never seen the gp, now it's a friday night, and I think I have an infection, because of its location, it makes me worry about my brain. I dont want to go to A and E I'll feel I'm wasting their time. I know my tumour is stable from a very recent scan. Will I be ok til monday when i can get an appointment over the phone? Sorry for the long windedness ha and that's a story I've tried to make as brief as possible. Thank you for taking the time to read and hopefully for me, someone can help? Many thanks again, all keep safe and take care Sam