I agree with the warm shower suggestion. I don't understand how it works, but I always feel better after taking a hot shower and putting on some clean clothes. Whether I'm coming down from stimulants or in withdrawal from any given substance.
If you're going au naturale with your comedown, the best things you can do are: Fluids; amphetamines are severely dehydrating, so make sure you drink plenty of water, but you also must make sure you balance out your fluid intake with the proper amount of electrolytes. This is why gatorade/pedialyte and similar drinks are a good option. I'll make the assumption that you're appetite is non-existent, but eating is an important part of restoring your body to homeostatic functionality. I would suggest nibbling on some bread/toast and washing down each bite with your drink. Last but not least, sleep. It's not understood why sleep is essential for survival, but in your case, a good rest is key to full recovery.
I'm sure by now you're probably through your comedown, but at least you'll have a tid bit of knowledge for if you ever decide to use stimulants again.