Hi, I am an American Board Certified Neurologist with vast experience in diagnosing and treating neurological & all health conditions including gastrointestinal conditions and I am very glad to help you with your health concerns.
I see the pain is on and off which implies most likely this is not anything serious.
Since he is on blood thinner the main concern is whether he has developed and gastrointestinal bleeding, however if this is the case then the pain will be constant unlike in his case it is intermittent so this does not appear to be secondary to any bleeding.
Also he has some diarrhea and this points towards conditions like gastroenteritis or IBS (irritable bowel syndrome) etc causing the pain rather than any bleeding etc. While these conditions also require evaluation by his doctors but you guys can wait for now. If you guys can get the scan done tomorrow then after the scan report further decision can be made so there is no need to visit the hospital now itself.
If he develops symptoms like severe dizziness, sweating, vomiting, or further worsening of the pain then not to wait for tomorrow, instead to visit the hospital today itself, but if he remains about the same as he is now then there is no need to visit the hospital now, rather the decision can be made after the scan tomorrow –depending upon its report.
Please let me know if you have any further questions. And please click a positive rating (preferably 5 Star/Excellent) to credit for the time & effort put by me in answering your health question, and this is the only way I will be credited for my service to you. If you have follow-up or additional questions you can ask them after the rating too.