Welcome
Craftwork
Anemia after RNY (and the DS) is pretty normal since most of where we absorb iron is out of the picture.
As far as diarrhea, what are you eating daily? First, clean up your diet if carbs have made a re entry into your eating habits. Go to water and plain meat for a couple of days. You should clear up and two days will not make a large impact on vitamins ect levels. Then start reintroducing foods slowly and keep track of how your system responds. Something is giving you fits and the only way to find it is an elimination diet.
It could be lactose, an artificial sweetener, some react to things like onions, type of fat, eggs, just about anything which is why water and one plain meat for a day or so helps clean you out.
Also if you aren't on a probiotic, try it. It may actually make it worse for a week or so but keep at it. Just means your gut had bad bugs in it.