An Aveeno oatmeal bath may help too. Oatmeal helps itching.

As others have mentioned, some meds and some medical issues can cause itching and/or dehydration. Low thyroid is one that comes to mind.

Have you changed laundry products recently? We can be sensitive/allergic to those too.

Water is the best for rehydration. Avoid drinks with sugarr or salts as both interfere with fluid absoption.

I hope you feel better soon!