painful uterine spasms during menstrual cycles

Question
Dear Dr. Eloise,
       I own a 7 year old pomeranian dog, vaccinated as per schedule, with a past history (3 years ago) of minimal crusting around 5 nipples and adhesion of circumferential hairs and skin to the nipple. I had consulted a veterinary expert, who said that it was a false pregnancy sign.
  She never had any episodes of pseudo-pregnancy ever since, but now she is undergoing her menstrual cycle and seems to be in great distress. She has a thin build, and I can visualize her uterine spasmodic contractions at well placed intervals. This is first time she has experienced this. I would be extremely grateful if you would kindly offer your opinion and advice.

Thanking you,
Dr. Srikar

Answer
Hi there,
When did she first start showing signs of coming on heat? I would be a little worried that she has a pyometra or endometriosis if she is painful. Has she got a normal temperature? Is she eating? Do you have a local vet you can take her to, to get her examined?

Eloise