HI, I read your question thoroughly. Being a cardiac patient you need to know that Warfarin is a medicine that causes thinning of blood but it also is the main medicine that you should use alongside the other medicine that you are taking. Human gut(intestines) has a very rich blood supply through out. Warfarin sometimes causes small vessels in intestines to bleed( because the blood becomes very thin which causes it to leak). These minor bleeds in intestine cause formation of clots which are passed down the rectum as blood clots.the discomfort that you feel in your stomach is also because of the warfarin induced distress of the gastrointestinal tract. The first thing you need to do is to relax and not to worry about it. The second thing you have to do is to get you PT/INR done, as this test is necessary to show us whether your INR is in normal range or elevated, because the latter is most probably the cause of blood clots. If your INR turns out to be elevated then the only treatment that you require is to slightly reduce dose of warfarin that you are taking. And yes you need to continue with the rest of your medication;Furosemide, thyroid medication. Finally get an appointment with your cardiac physician whenever convenient. I hope you find this helpful Regards! Dr. Abdur Rehman Alozai.