That sounds familiar. I too have had regular excessive itching in the past (still get it a bit) and could not attribute it to anything. Was worse when I went to bed for some reason, even though, during the winter I kept the vest on, so it wasn't as if I was suddenly in contact with anything different. All very puzzling.
It isn't always changes you have or have not made but the manufacturers of your regular detergents, deodorants, soap etc. that can alter. Antihistamines from any chemist will help as it stops the itching as the more you scratch the more you itch. Calamine lotion can help. Wear cool cotton clothing as heat will also make it worse.
Just had a thought - I have PLE ( Polymprphic Light Eruption) which is basically an allergy to certain sun rays. Has got better as the years have passed and didnt start till I was 16, but think that started with intense itching. Google it and see if there are any similarities?