Itching all over no rash for three weeks. tried benadryl (diphenhydramine) but it don't work it gets worse at night?

Needs an evaluation: There are a lot of reasons to be very itchy, from scabies infestation to eczema to liver or kidney disease. Each one needs different treatments so you need to get evaluated by your physician asap. In the meantime, use gentle cleansers on the skin and moisturize at least twice daily to keep the skin calm. And try your best not to scratch!

Need Evaluation: You should be seen by your primary care doctor. You could have a number of different issues- thryoid, liver, kidney, etc. Blood work and evaluation may be mandatory!