Pain when stretching

Question
My dog jumps up at the door when my husband comes in from work and on Friday evening when she tried to climb on the settee she yelped in pain, but she can run down the stairs play with my other dog and shows no sign of any pain or lameness when walking, she can lie down and get back up with no problems it only seems to hurt her when she tries to climb or run fast, i have left her for a few days to see if it gets any better as she doesn't seem to be in any kind of pain do you know what this could possibly be?

Answer
This could be just about anything, but it is most likely something with her back; she needs to be seen by a veterinary chiropractor.
http://www.avcadoctors.com/search_for_avca_certified_doctor.htm

If you have trouble finding a veterinary chiropractor, locate a group who does dog agility and start asking there. http://agilitynet.co.uk/frontpage.htm

In the meantime, gently run your hands all over her, and if you feel a spot that feels warmer to the touch than the surrounding areas, ice it down for ten minutes twice a day. Keep her confined so that she gets total "bed rest" for a few days. Acupuncture might be beneficial, also.

Things to watch for:

A healthy dog should:
  Do full yawns.
  Do complete stretches front and rear.
  Do full body shakes from head all the way to tail.

If the dog aborts any of these, it is usually due to pain issues.

The spine/body should look totally straight from the nose all the way to the tail. If the body starts curving to look like the letter "C", something is wrong.