I'd say the doses have been switched a lot and by too much at a time. The 50 last night was a clear sign that the dose of 3 units is too much, even for a 400. If he were mine, I would go back one unit, hold the dose for several cycles, getting midcycle numbers whenever possible. The midcycle numbers will show you if he drops too low and then bounces back up for the preshot number. If he is more flat across the cycle and has shootable preshots, then raise by 0.25.
The protocol and beginner's guide we put together is in my signature in blue. Both may be helpful. Also, you can post your numbers here daily, get advice and ideas about what might be going on and how to adapt the dose to help.