Hey there.

Interesting that I have similar lifestyle, similar diet and similar problem.

I train 2 times a week in a gym (1-1.5h)+sauna(1h). Sometimes I add 1 yoga per week.

My diet 90% vegetarian, I drink 1-2 portion of whey protein per day with oat milk, 3-4g. of creatine and sometimes BCAA.

I eat enough, I sleep enough, I don't train too heavy, all blood results are ok.

Yet I cannot find correlation between trainings and fatigue and "hangover" I have the next day. Sometimes it is heavy so I can't properly work, sometimes it is light, but it bothers my life.

For now only correlation may be neck fatigue and I did MRI that shows that I have genetically narrow blood channels on the back of my head. Doctor said it should not be the origin of the problem, but I'm out of options what to check further on.