That's normal. Mine do the same. As long as they have food every day and eat a little or a lot I don't worry. Even if they go a day or two without eating I don't worry. I will keep a closer eye on them and feed something I know they can't turn down. Mine has never gone more then those couple days then they are back to being pigs again.
Russians are very an extremely dry (all year long) climate. Adult Russians may not drink much. Mine has never taken a drink other than coming out of hibernation. She’s outside and our climate is fairly humid so I imagine she doesn’t feel the need. It might be different with an inside tortoise or if your climate is very dry
I soak her once a week anyway; it gives me a chance to check her over and weigh her.
Okay, he’s been a little stressed so won’t be doing everything exactly on schedule but he fell, right? So it’s good you are keeping track. He’s still eating so that’s a good sign.
Has he peed? Probably in the soaking bowl?
It’s time for you to get us some pictures of your enclosure and feedback on the temperatures under the basking light and so on. You can put a picture in by using the “upload a file” button if you are on a web browser. If you have the app on your phone, it’s a little easier as there is a little picture of a camera. If you haven’t read it yet, read the care sheet for Russians: http://www.tortoiseforum.org/threads/russian-tortoise-care-sheet.80698/. Then you’ll know the temperatures and lights we need to know about.
I’d actually start a new thread for this so people don’t think your question is just about food, which is the title of this one. Or go back to the thread you started when he fell. We want to make sure people will understand you have a new question; the new thread makes it easier to see.