Chronic constipation after starting solids. HELP

We started solids in earnest with our 6mo about three weeks ago and she has been super constipated ever since. She went nearly a week without pooping last week (which was the limit the pediatrician gave us before bringing her in) until she finally went after I loaded her up on pear and plum purée. We're now on day 5 of no poop again. I've again been giving her plum purée at every meal as well as about an ounce of water, but it doesn't seem to make a difference. What else can I do?