Your dog's body is going through hormonal changes and sometimes they will feel sick to their stomach and eat grass which causes them to vomit and will have looser bowel movements. Many dogs will also have a behavioral change during their heat cycle and appear to be more intolerant of other female dogs.
The symptoms you are describing typically only last a short while as her body adjusts to the hormone shift.
Similiar symptoms can be seen in a dog with a serious vaginal infection, but the discharge is pus filled, smells bad, there is diarrhea and vomiting, frequent urination and thirst, abdominal swelling yet bones may start to show. This typically happens to older dogs and is typically seen 30-90 days post heat.
So I believe your dog is acting appropriate. Here is some additional information about the dogs heat cycle.
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. This can last from 4 to 21 days though the average is 7 days. 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.
Hope this information is helpful.