Re: "My ph was down so I used sulfur to get the proper ph level " Did you mean your pH was UP? Sulfur lowers pH. Lowered pH (higher acidity) is what you want for blueberries. But you didn't say when that was that you did the sulfur treatment. If it was just recently, it may not have time to make a difference yet. If it was last year, have you checked pH recently? Not everyone reports this, but in my experience, with my Ohio clay, for plants in the ground, lowering pH is a process that has to go on continually. Whatever you do to the ground around your blueberry is gradually cancelled by interaction with all the ground around it. So you need to do pH lowering at least every year, if not twice a year.
But yes, agree with tom, yellowing leaves is often a sign of too much water and not good enough drainage. Clay soil isn't a terrible thing to have, but it doesn't drain fast / stays wet longer. And these two factors interact. Lots of rain is going to wash out the effects of your pH lowering treatment faster.