Let me just say, I don't think anyone posting on this thread is recommending calling the vet for some minor thing. This is a pregnant mare without known breeding dates so no idea of a range of due dates, who according to the OP is not eating normally, who is exhibiting progressive fluid retention and edema even with increased excercise, and who might have had fescue exposure.
The OP came to the forum asking for advice and titled the thread "Somethings not quite right." None of us on this thread are vets, but we all have varying levels of experience and made observations and offered suggestions when asked out of courtesy and concern for the horse and her owner.
As far as experience-- each year for the past 15 years I have bred, foaled, raised, and cared for 1-5 pregnant mares and foals of my own. Prior to that I worked for a breeding farm for 4 years and among other things, I attended 8-10 pregnant mares each year as the "night watchman" for them during breeding and foaling season. I was usually the main person there to foal them out. It was usually "my call" as to whether to call a vet or not during labor and delivery, and most often, I did not.
I don't call the vet for every little thing. I am pretty conservative about vet care. With my own mares, I closely observe, but I allow the mare to live and carry her foal as naturally as possible. Through the years I have learned to do much of my own "work" and I am pretty comforable with many situations. I also have experienced friends and colleagues in the horse business that I talk to and we share experiences and ideas.
I agree that many things do resolve on their own and are "no big deal" and don't need veterinary intervention--- However based on the info the OP has shared and the photos she has posted, if this were my own mare, I WOULD call my vet.