PINCH ~ your condition sounds very serious to me; so the best idea would to be talk all these things over with your DOCTOR at your next check-up. I might have suggested something for the heartburn and nausea symptoms, but again becuz of the seriousness of your health issues, you would have to see if that would interfere with the other meds you are on.
When a medication causes stomach irritation, it is usually recommended to take your meds WITH FOOD, to lessen that side effect; is that a possible solution? That may or may not help the nausea; but maybe very low-dose gravol could help a bit, BUT again, you would have to OK that with your DOCTOR first to make sure there are no contra-indications (interference with other drugs).
The other solution would be to watch the kind of food you are eating: focusing mainly on veggies, fruit, very lean meats, and natural whole grains. Watch how much 'perked' coffee you drink as well as spicey and acidic foods and beverages (like orange juice) as these can irritate the stomach a bit.
You said exercise wasn't recommended, so how about just going for a short stroll each day (starting with about 5 minutes at a time and working your way up to 3-4 times a day)? Again, make sure to OK this with your physician first, but walking is often the most recommended form of exercise for people recovering from heart attacks and strokes.
* Honestly, just *eating healthier* may be your best option right now. It is possible to lose weight or even just maintaining by eating better. I sincerely wish you the best and hope your health improves very soon. Again, check everything out with your DOCTOR FIRST ...
ROSEBUD