Don't know if this will help but a person on Tumblr had a uni prof who said 'if something is worth doing, it is worth doing poorly'. So if you can't shower, wipe certain areas like armpits, genitals, feet with a wet towel or wet wipes. Brush your teeth for 30 seconds or 10 seconds, it's better than not at all, or gargle mouthwash, someone even suggested putting toothpaste in your mouth and swirling it with water. Of course overtime there will be side effects but when you just cannot get yourself to do things, it's better to do the things that are worth doing poorly than not at all.