Hi everyone. I'm new to this site..hopefully someone can help. My sourdough "mother" is now 11 months old and in the early days my sourdough rose beautifully. Recently, however, I'm getting very little rise in both the first and second proving. I keep my "mother" in a jar with a screw cap and when I don't bake regularly I put it in the freezer, take it out the noght before and feed it before using. It has lots of bubbles and look good. I've also noticed that recently the smell is not as acidic as it was and has developed a pungent smell instead. There's no mould in the mixture. Please help!!!!