Hello! Thank you for the query. Your nausea and stomach ache can be caused by partial bowels obstruction due to colon cancer. Over the age of 50 the risk of colon cancer rises and every symptoms from gastrointestinal tract should be checked with this disease. You should also have constipation or/and diarrhea, weight loss, bloating. Blood in stool can be present. Nausea can be also caused by blood pressure drop (according to your heart disease), blood sugar level drop, internal ear diseases, brain issues (like tumor or infection), stress or medicines (I`m sure you are on beta-blocker, some types of beta-blockers are better tolerated by patients, others get side effects from them, so it is worth to try different beta-blocker). I suggest you to start with colonoscopy and stool tests. You should also check your blood pressure and glucose level when nausea appears. Discuss possible side effect from medicines with your cardiologist. Neurologist and laryngologist consult should be the next step. Hope this will help. Regards.