Same here for me with moderate HBP which sometimes fluctuates and taking low dose lisinopril. Sometimes eating highly salted foods can spike the BP temporarily. Sometimes not drinking enough water is an issue too for me. Better hydration gives the kidneys more juice to regulate the sodium levels in the blood. Soy sauce I love but its concentrated with salt—sets me off too.
There is a low salt soy sauce.
I was just diagnosed and given 10 mg linisopril. Bad reaction to it (alleged mental status, more than normal, heh!) and a pretty obvious rash. Now on 25mg of metopolol.
Try Bragg Liquid Amino, a great alternative to soy sauce.