I wouldn’t get too stressed, these things happen (stomach problems are the worse though, since it takes a while for your system to bounce back…even when you think you’re fine). It took me a good 3 months before I was able to gain properly again when I had a bug.
Something I’ve noticed with your training is that you almost seem “wiped out” before the actual work sets start. Also, some things suggests to me that you probably have pretty poor recovery (like many do). At this stage, gains (especially in bodyweight) should be a bit more “flowing”, which again says to me, that maybe you’re fatiguing/training more than you’re able to rebound from (fatigue/volume is greater than the growth it’s providing).
I’d suggest in the meantime, a low[er] volume approach to training (especially until you properly get back on your feet again. Keep warmup sets to a minimum; general loosening up, followed by 5-8 reps for fist warmup set, then 3-5 reps for second warmup set, then move onto work set(s). Do 1-2 sets/exercise for upper body, and 1 set for lower.
Another thing (can’t remember how much you’re taking in just now), but I think that increasing carbs would be a good idea at this time, especially considering how slowly weight gains came before (this will also increase capacity/strength). Higher carbs during bulking is fine, so long as it’s not something stupid like higher than 55%. Some people get diminishing returns (excessive fat gains) when much over 40% of total calorie intake, but it’s something you’ll have to discover. Dieting is a different matter though (lower carbs usually always “wins”).
Hopefully all that makes some sense ![]()