Ok, so how about relaxing about it for a few days?
Just follow EAS order and follow his cues. If he puts out tired cues, try shifting him to a new activity and if he's still grizzly, put him to bed. This will allow you to see what his natural rhythms are doing at the moment and may help you keep your sanity. I actually took my watch off for a few days and I had a much happier child because whilst I was winging it, I did have a routine - not a schedule - and that meant he knew what was coming next. When he woke, he got fed, then he played, then he slept.
Keep a nap in the pram or something if you have to but make sure you get out as you don't want to be getting cabin fever - not fun and can spiral downwards quite fast. Its a lot more important for you to be relaxed than most people give credit for. Babies pick up on your stress/anxiety and mirror it back to you.
Can you bath him in the morning? I had forgotten about your back issue, sorry.