Colleges will not rescind acceptances based on quarter grades. Keep plugging away and working with your tutor and, hopefully, your D’s will become C’s (or better). It’s possible that your colleges could rescind if you end the year with D’s in two classes  as final grades. But in the unlikely event that this happens, you can appeal the decision by providing documentation from your tutor and your teachers showing that you did try hard and weren’t just suffering from “Senioritis.”  In addition, because you already had a “D” on your record BEFORE you were admitted, the college folks shouldn’t be shocked to see yet another D on your report card … as long as it’s not two of them! It isn’t necessary to contact the colleges at this point, but if it would make you feel better to do so, you can certainly send an email that explains to them what you’ve already told “The Dean.”