There are some different possibilities for the issue here.
One is that she is acting off as she is in the phase of her heat cycle when she is ready to be bred and would like to find a male for that purpose. Dogs are normally in heat about three weeks and days 9-14 are the most common days for breeding.
Another is that there is tissue overgrowth extending into her vaginal and vulval area causing the excessive swelling and making her a bit uncomfortable.
And it is possible that this heat, due to her age and the number of heats she has gone through before, that she is coping with a uterine infection called pyometra which you can read about here
http://www.marvistavet.net/html/body_pyometra.html
I'd suggest a vet check up for her to make sure this is not a health issue causing this restlessness.
At home you can check her rectal temperature. Normal temp in a dog is 100.5-102.5 Fahrenheit (38 - 39.2 Celsius) so over 103.5F or under 100F would be a concern.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics