Ok, thank you for that information.
Trembling is quite a non-specific sign and we can see it when a dog is in pain (e.g. tummy cramps), is anxious or has a fever.
Similarly, a drop of blood in the poo is not diagnostic of a particular condition and may occur for a variety of reasons including bacterial infections, parasites, eating a rich diet, eating inappropriate items (bones, toys, plastic etc) as well as many other reasons.
If she is still bright, active and appetant this is reassuring. I would also want to quickly check her gums to ensure they are pink and wet. Similarly, her abdomen should be soft and comfortable rather than tense and painful when gently pressed.
Most cases of upset stomach will resolve within a day or two. Help things along by feeding a bland diet of boiled white chicken and rice little and often. Do not give any dogs food, chews or treats as these may be too rich. Encourage water drinking and you can add some of the water the chicken is cooked in to improve the taste.
Allow her to rest and do not force her to play or exercise (though do give her outdoor access to allow her to do her business as frequently as she likes).
If not done in the last few months, it would be prudent to rule out internal parasites by giving her a good quality wormer such as Drontal or Panacur as soon as possible.
You can also give her a few days of probiotic paste e.g. protexin prokolin or canigest to stop the diarrhoea/blood. These can be purchased online or from pet stores or the vet. A prescription is not necessary.
Check her environment for anything she may have gotten to such as rotten food in the garden, a chewed up toy, rat bait, antifreeze etc. just in case.
Continue to monitor her closely and you should find she improves with time. If she develops any symptoms such as lethargy, reduced appetite, vomiting etc. this would mean we need to change our plan and she may well need to see a vet. The same is true if the diarrhoea becomes more profuse or if there is more blood (which may be red or tarry black).
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