How do I make grandma more comfortable when she doesn't even want to wear clothes or be in her own skin?

Dehydration and dementia issues are both valid. If she has OCD, that could be part of it (picking at skin is common). Whatever the issue, she certainly needs some medical attention.
Carol

Arthritis will cause your hands, knees,back, etc to 'swell' making it uncomfortable to be in your own skin. I noticed my arthritis first when I woke up, and my 'hands felt too TIGHT' I think this may be what is being felt.

Or course I am just going on my personal experience, but it would be worth while to ask her doctor about this.

With on-set dementia, she may not be able to express herself completely. Perhaps her under garments are too tight, or her skin is dry. Offer a soft LOOSE robe, and some moisturizer and see if that alleviates the problem.

Dehydration is one of THE most common problems with many adults, senior and otherwise. Offer TEA (instead of coffee which can further dehydrate a person, since coffee acts like a diuretic) and offer hearty soups, smoothies, and just SMALL glasses of juice or milk at a time.

We used Jello, and pudding and icecream and other forms of HIGH liquid meals to get fluids into mia Madre (my mother). Also I would have her 'taste' soups throughout the day, or chilled soups on hot days, and milk shakes are a daily occurrence!

Angela and mia Madre

GDaughter, is there any type of drink she really likes such as a fruit smoothie or something that will get her to intake fluids? Or watermellon chunks or some other fruit that has a high water content. For the peeing there are those wonder garments - Depends. There are also portable Female Urinals as well, just in case for quick emergencies. They almost look like a little pitcher with a flat top. Just some more ideas. But best to call her doc and run it past him as well.

Ahhhhh; poor baby! So sad to hear of grandmother's suffering and confusion. Definitely sounds like dehydration. Seek medical help. You are not alone. Many experience similar encounters with loved ones. What a wonderful granddaughter you are for seeking help! Take care.

Pirates, Yes she has on-set Dementia. She maybe dehydrated it has always been hard to get her to drink but its even harder now she doesn't want to drink because of all the peeing.

Perhaps you need to take her to her doctor, there may be some inflamation? It maybe her meds making her hot? Does she have on-set Dementia? Is she dehydrated, it's been hot in some areas. Just some ideas to think about.