I get Propel powdered drink, it's by crystal light and Kool-Aid powder mixes in the grocery store, I mix and drink 2 glasses of this for some electrolytes, get down ~10 glasses of water and eat simple carbs-noodles, rice, oatmeal- and do NOTHING except lay on the couch most of the day (there is a lot of Law & Order out there) I feel a little better by late afternoon. I usually am better the next day and want to charge out there and make up for lost time, it is really hard to convince myself to stay quiet (like a dog straining at the end of the leash) but if I do that I am back where I started. The following day I may do easy things where I can be up and around in the house-simple paper work, laundry, easy weed pulling, maybe grocery shop-where I am moving around, nothing strenuous physically or mentally, for an hour at a time with resting 15-30 minutes in between. Then, the 2nd day, do at it. Keep a diary and see how the crashes relate to high stress, long periods of complex concentration/thinking, physical exertion, life events, long periods of time on your feet. I found out what my triggers are and manage my time better, starting with 2 hours a day of physical activity and 2 hours of deep thinking and slowly increased my time from there. Look up the 2003 essay "The Spoon Theory", by Christine Miserandino. It was profound for me and made a huge difference.