My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today. Let me explain the heat cycle first then I'll go into more detail about your dog specifically and what seems to be happening.
Female Dogs go into heat at any time between 6-12 months usually. The average heat cycle for a dog is approximately 3 weeks but for some dogs it is longer and for others it is shorter. Some as short as 10 days and some as long as 4 weeks or more. Usually your dog will go into heat every 6-7 months though again each dog is different and can go back into heat as early as 4 months or not for 12 months. Most however are average.
During the first part of a dogs heat period you will notice swelling of the vulva, possibly an increase in urination and bleeding. If there are male dogs around you will notice them hanging around her. This stage generally last about 7 days and she will not allow males to mate with her during this period
The second part of the heat cycle is when she will accept a male and breed. Usually a female will lift her tail out of the way. Usually bleeding has stopped or become straw colored at this point. This can last from 4 to 21 days though the average is 7 days. Many expert say the 9-10th day of heat is the optimum day for breeding. It is during this period of time that you will want to allow mating. Most breeders allow the dogs to mate every other day during this period.
Then during the last stage of heat she will be less willing to breed as she is going out of heat. This stage can again last from 4 to 21 days as well but averages 7 days. Each dog is different so some evaluation by the owner is necessary. The whole heat period should be approximately 21 days but as stated can be longer or shorter depending on the dog. Here is an excellent website with pictures to illustrate a female in different stages of heat.
The above is general information on the heat cycle. Now some dogs do experience discomfort during the heat cycle especially the first one when the tissue is swollen and will cry and whine. You can use a heating pad or put warm water in bottles to let the dog curl up with. That might provide a little relief.
However, there is a dangerous and even deadly condition that mimics a heat cycle which is a uterine infection called pyometra. Pyometra generally occurs 60-70 days after a heat cycle. It is usually seen in older unspayed females but can be seen in any age. It is diagnosed by ultrasound showing fluid in the uterus. There are two types of Pyometra (open and closed cervix) Symptoms of open cervix Pyometra are a vaginal discharge that may be pus or bloody, lethargy, anorexia, increased thirst and urination, vomiting and diarrhea, and abdominal swelling though the dog remains fairly healthy due to the infection draining from the body. Closed cervix Pyometra symptoms are the same without much of a discharge, they appear very ill, there is usually weight loss and abdominal swelling and is much more extreme. Dehydration, shock and death can occur if not treated aggressively.
Treatment for pyometra is spaying or antibiotics if caught early enough. The longer she has pyometra, the greater the risk of her not surviving surgery. If you think this might be the cause, I'd get her in to the vet as soon as possible. Some vets are open today and tomorrow though you might have to call around to find one.
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.