It is hard to say, about the food. If it is her anal glands, pooping may help. When things are working right, that is generally when the anal glands are emptied. If something is blocked, or if it isn't the anal glands at all, food may make it worse, or it mayhave no effect. If she is not feeling well, she may not even be interested in the food anyway.

I guess I wouldn't feed her, unless she is really begging for food, and if she does, maybe 1/2 her normal portion.