My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. I've been breeding for over 20 years. It will be my pleasure to work with you today.
Some dogs, especially first time young mothers, seem to have a hard time with the beginning stages of labor. I usually will put a pen around the whelping box and as you are doing, sit in the whelping box with the female. I usually will start massaging her and stroking the abdomen. This often helps a dog calm down.
You will need to be prepared for her to not take the whelping well. Often dogs displaying these symptoms during early labor may end up nipping a pup as they are being born. In some case, they may not stop when biting the umbilical cord. The pain of whelping can also cause them to run erratically around and damage the pups in that manner as well. You will need to be prepared for this with towels, scissors, an aspirator, etc. I know you have experience but be prepared for the worse with a dog reacting like this during early labor. Here is a great site on whelping and another on raising orphan pups just in case she doesn't want to care for them.
Here is a site for information about difficult labors.
Now a dog can develop eclampsia before she delivers her pups and symptoms can include trembling. Other symptoms include muscle weakness, muscle spasms, tremors or seizures, limb paralyses, she needs to be seen now as it is possible she has eclampsia. Calcium supplements, Tums, cottage cheese or goat’s milk may help, but it might not reverse the symptoms quickly enough.
Here is sites with more information on this.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.