First sourdough loaves

The loaves of bread made on Sunday rose beautifully. The flavor however was not so great. The bread had a sour flavor, but also a bitter aftertaste. I was using rye flour that I had in the freezer and maybe it was rancid. Rye flour will go bad faster than white flour. I have decided to continue to feed the starter for another week with unbleached white flour and see if the bitter taste goes away. If it doesn't improve I may start the culture over with fresher flour. My son Tom and I are the only people in the family who ate the bread. It didn't bother Tom, although he thought it tasted weird. On the other hand, I had some digestive issues that might be related to the starter since I ate some of the bread warm and I know that yeast will stay active in bread for a day.