Thanks for the quick reply,
While I cannot diagnose this over the internet I can tell you the following :
In direct answer to your question : Tums are mainly calcium carbonate and are very unlikely to do your dog any harm in terms of toxicity and could serve a useful function if your dog has primary indigestion. You would dose your dog with Tums on a pro rata basis between your dog's weight and a human weight.
If you want to be 100% safe you should have a vet check your dog over ASAP, however I am aware that many owners treat such situations in the following way on a home remedy basis and report success. The basis of this approach is to give your dog's gastrointestinal tract a rest and then gradually return it to normal function.
A. Starve her for 24 hours but make sure she has access to water.
B. The next day feed her four or five small light meals in the day. These meals should be the likes of chicken
, fish, scrambled egg etc. with a little rice.
C. If she pick up on this diet gradually reintroduce her normal diet over the next few days.
Of course if this does not work or if your dog deteriorates you should see your vet.
If I have not covered your question fully enough or you would like to ask more I will be online for the next hour or so and I will be at your disposal. Scott Nimmo BVMS MRCVS