I took MSM along with collagen years ago for skin and hair, it does work well. I also had dark circles under my eyes after a good nights sleep. Unknown to me at the time, I had a parasite infection. It wasn't until about a year after the dark circles showed up that I knew I had a problem.
Both MSM and Grapeseed have some anti- parasite or anti-candida properties. The brain fog could be a symptom of die-off. You might want to try a basic parasite cleanse, it's more common than most people think.