I am sure that besides the discomfort you must be having a large dose of buyer’s remorse about your new bike. I had a similar situation when I purchased a new bike a few years ago. I always had drop bars but after 30 or so miles on my new bike I was in great pain. I went back to my LBS and they compared my old bike to the new one. In two minutes they discovered that the stem angle was the same but the length of the new stem was a few millimeters longer. They swapped out the stem for a shorter one and the pain disappeared. With a little experimenting on your stem angle and length I am sure that you will find that your new bike will be a joy to ride. I know that with a little adjusting you will find the perfect fit and will begin to enjoy your new ride. All the best.