Did she chew up something that she shouldn't have? Ask your vet about maybe a x ray. Expensive, but she may have some sort of blockage.
Thankyou for your comment, no she hasnt recently.
We have changed to pedigree brand of food we thought it might of been too strong for her or something ?
Welcome....Yes, there are a few reasons for this: Panting is a sign of pain!!!!......Vomiting & NOT able to poop signals an Intestinal Blockage.....Has she eaten anything unusual like a toy, ball, sticks, socks, etc?
Also, this could be a Stomach Bloat/Torsion.....Bloat is FATAL quickly! Blockage is also fatal, but not as fast......
You must seek medical attention for her Immediately......IMO, You have an emergency setting up......
Please, let us know how it turns out & good luck.......I'll be thinking about her........Karla