Mama,
You say 4 days fermentation. It does depend on how hot your kitchen is? Mine turns to curds and whey before 4 days if i leave it. Sometimes i strain it and then leave on counter for a further day.
I think there is something wrong with my current kefir grains. They don't seem to grow. I've done many batches on and off. I leave in a little milk in the fridge when not making any kefir.
The last batch had a strange taste. I got this lot from ebay. The last lot i had, grew alarmingly, so i know the difference. I had frozen some, as was having a break from it, and then my freezer packed up. So threw them out.