Itchiness all over body

Hi doctor im a girl and 17 years old…

I currently experiencing an itchiness on my back,nape, left underarm, scalp and especially on my private area,I also had difficulty to sleep due to the itchiness.it had been a couple of months

At first it was on my genitals and it was so itchy that I can’t help but scratch it then it started to swell up and having a rashes, redness. So i took a pain killer, flu/allergy pill,antibiotic and I will put a warm water towel on it for a minute. then in the morning its back to normal so i took the pills and put the warm towel on my genitals for a few weeks then I stopped because I thought its back to normal. (This was around November to December 2020)

Until this month on Jan 2 the itchiness on my vagina is back again and I thought it was because of an eggs that I had for breakfast because the itchiness was back when I ate it so i took the pills and put a warm towel on my genitals, it lasted only for days then back to normal.

Also i noticed I’ve been having an itchiness on my nape, left underarm, scalp and my back. I thought it was due to the shampoo and soap I used so I changed them because I have a sensitive skin but It weirded me out because usually when I experienced allergy to soaps it wouldn’t be this and usually I wouldn’t have a problems with shampoo that caused my scalp to itch so bad that when I took a shower it’ll sting. Also my scalp started to have a scalp flakes, it sting when I took a shower. Sometimes I’ll wake up due to the itch when I sleep…

Then yesterday my genitals started to itch again not only on that part but my scalp,left underarm, nape and back even after I changed my shampoo and soaps. It was so itchy that I couldn’t sleep, I’ll fell asleep then wake up again because of the itchiness … I took the pills and the warm water but it didn’t work this time, there were a rash, bumps, redness and I noticed when I scratched there will be a dust falling off at first I thought it was dust but then it was not it looks like a dead skin or skin flakes? I don’t know how to say it, there’s also feeling of burning, It was so itchy. I don’t have a problem when urinating or pain…

My nape had rash and a burning sensation after I scratched it, my left underarm were red but not painful or have a burning sensation. As for my back it was painful when I took a shower and had a burning sensation…

I don’t know what to do and I’m so worried if it a serious illness, and my school are starting on 20 Jan I can’t go to school like this … Please help me