Hi dude,
I experimented with vegetarianism many years ago, but didn't know about the dangers of cereal or soy foods, so included a lot of these in the diet and also beer. Not surprisingly, I felt tired all the time and had digestive problems.
Also tried mainly plant based raw food diet for 2 years, much later, with no drugs or alcohol. Felt physically more energy but very bored with the food, and started eating less to avoid the 'same old same old'. Mentally, a bit dull.
More recently I settled on low GI with intermittent fasting, which is semi-ketogenic. Much more energy and more interesting food; choice of vegetarian or not. I found the biggest difference in alertness when switching from processed food (especially cereals and processed meat) to organic unprocessed food, most especially stuff I have grown. You do have to do your own food preparation right from scratch but this is also a calming, pleasant task for me.
But, everyone is different, and even our dietary requirements at different times in life are different, so it's worth keep trying new diets until you find one that really works well for you.
Re: creatine: this is a fairly comprehensive study:
https://www.fda.gov/ohrms/dockets/docke … vol112.pdf
Side effects are in section 7. I don't like the sound of cancer dangers (section 7.6)
Good luck and let us know any results,
Best,
AR