Maybe try a new bone? Mine only gets Marrow Bones from the local butcher... but generally when I see something that seems odd with a food I stop giving it to him ... he may love it... but he'll love the next thing I give him too.
Yes, many many years ago with my first and last experience giving rawhide. Just keep an eye on her that she is eating and drinking water ok. Sometimes they may have 1 or 2 vomiting after eating something like that, (read up on why some rawhide or sticks are not good for your dogs) but should be thirsty and drinking lots of water. If she isnt eating or drinking you might want to take her to the vet just to make sure shes okay.
Is this always in the morning before she gets her breakfast? Could be from an empty stomach. The chewing action can trigger a release of stomach acids, and/or bile. Common for some dogs to throw up foamy white/yellow stuff in the morning from having an empty stomach.
Try giving a snack just before bedtime of a couple of dog biscuits, or anything else you like to give as treats and see if it helps.