Itchy skin all over, no rash and general unwell feeling.

Hi - I have developed a very bad itch all over my body this past week. It started on my lower legs and is now on my back, stomach, arms, face - everywhere. Note I have not changed any detergents or products that could irritate. I also have been feeling increasingly tired and experience joint ache, especially when climbing stairs I notice it. Finally, and I don't know if this is connected, but my hands have been increasingly sore, almost arthritic in the past few weeks. I am a 29 year old female, have a history of iron and b12 deficiency and therefore decided three days ago to up my iron intake (spatone) as I was concerned this was the cause but it hasn't helped. I have taken antihistamines the past couple of days but no change - it doesn't help at all. No sign of any rash from what I can see. It occurs all day, no matter what the weather or climate is like. I have no idea what's wrong. Would appreciate any help.

* I wrote the above yesterday, now I notice some redness but I don't notice if that's from scratching too much?