I have mentioned before here...PPIs give me headaches.
Have no idea why...they just do...big time.
I take Axid instead. Works well in small dosages. I try to control my eating and drinking to help with digestion issues. I also take a magnesium tablet daily. If I have trouble with constipation, I take a sool softener. I am exploring natural things to take intead of or in combination with a low dosage of Axid to help cope with stomach burning, etc. Bottom line...I just don't do PPIs. Some doctors really push them. If you feel strongly they are not for you, don't hesitate to try something else. (However, I wouldn't recommend doing this w/o checking with a doctor and w/o taking something for your stomach...no need to walk around in pain and miserable!)

I too have gotten benefits from the B vitamins.
I take a B50 tablet and extra B12 as well. GREAT stuff!
I'm also a huge believer in the medicinal properties of exercise. This is one of the reasons I push myself very hard in this area.
However, if fatigue hits, it is IMHO, best to honor it. Sometimes we need to modify our exercise or not do it at all. Just get back on the saddle again asap.