Yes it is very significant symptom and suggests that the infection might have spread from your intestine to the other parts of body. Clinically it is called Sepsis and suggests systemic infection.
As you did not mention if you saw any blood in the stool, I am going to assume that it was non- bloody and it suggests that it most probably is bacterial. Also looking at your symptoms it seems like you have not taken enough water to replenish the loss of water due to diarrhea which has caused the racing heart. The most significant symptom that you have breathing irregularity and it needs immediate attention.
I suggest you do the following things:
1) Start a broad spectrum antibiotic like Tab cefepime to prevent the progression of sepsis.
2) Go to the nearest laboratory and get a blood culture done to rule out sepsis. Also get a complete blood count. Based on the culture sensitivity the antibiotics can be changed.
3) Increase the intake of water and other fluids to prevent dehydration. If you cannot take enough fluids orally, I would suggest you get yourself admitted in the hospital and take I.V normal saline.
4) Check your temperature regularly and maintain a record to check the progression.
5) Get a chest X-ray to check for lung pathology.
If the severity of the symptoms increases kindly consult a doctor for the aforementioned recommendations.