Steroid shot and NSAID?

Hi Dr. Marie,

Bare with me in my lengthy explanation :) I recently found out my mini-dachshund has a calcified disc toward the end of his spine. The day I took him to the vet, he was given a steiroid injection in the office and then prescribed Previcox. He began to have bloody diarrhea and I immediately quit the Previcox after 2 full doses and 1 partial dose. The vet gave him Pro-pectalin to clear it up and his bowels have been good since then.
I have since learned from a lot of reading that giving a steiroid injection and a NSAID like Previcox at the same time is life-threatening and is the reason my dog had the bloody diarrhea. I confronted my vet and he said that it was OK to give the two medications together (though I know it was not). My dog is now on Rimadyl, Tramadol, Robaxin, Sucralfate, and Famotidine and his pain finally seems to be under control.
Here are my concerns- Should I be worried that he is still in ANY kind of danger from the combination of the steiroid injection and Previcox that he was given? As I said, his bowels have been clear since stopping the Previcox over a week ago, but I am so paranoid that something could have been damaged internally or he might have ulcers etc.- even though I am no longer seeing the bloody diarrhea. Is there anything at all I should still be concerned about in regard to this?
Also, he has 2 days of Rimadyl left (he was given a 7 day prescription). Is it likely that he needs to stay on this for a longer amount of time along with his other meds? If not, is it safe to just stop them all at once?
Let me also just say that this is a well-respected vet center where I live and I have always considered the team of vets at this office to be very good. But, needless to say, I am very concerned and disturbed by what happened in this situation. Any feedback you can give me would be very much appreciated. Thank you so much for your time.

Hi again,

Thank you for getting back to me. Yes, Boner did have dark black diarrhea as a result of the Steiroid injection/Previcox combo. I should have mentioned that in my first message. You mentioned that this could indicate a more serious problem. He has not had this happen since quitting the Previcox. So, with this additional information, should I be concerned about any kind of problem still- even though his bowels are now fine. I am willing to get any kind of testing done to check for issues.
Thank you again.