Ninebark are generally easy to grow and not very demanding. What is the dirt like under the shrub? If it is saturated and the dirt is kind of stinky, back off on the watering. You might even stick a pitch fork in the ground around the base to help air out the dirt. I would just give it a good soaking every 4-5 days rather than water every other day and see if that helps. Once you get it through this first summer, it will be low maintenance.
Thanks for writing!