I think a self test is if food sits in your stomach, too little acid. Other than that I don't know.
As far as how long to take vitamins - did you have your levels tested? Mine tested low and I'm testing every 6-4 months.
Whey is milk protein. Do you need protein? Can you eat meat or beans?
Well I am told that I need the Whey powder as I am deficient in proteins ands I am not absorbing enough nutrients. I do eat red meat twice a week. The beans not so much, I am trying to get into the taste of them but yuck....