For the last year before covid, heart palpitations, when that happens get short off breath, ringing in ears and see black. i have low blood-pressure normally. diagnosed with ulcerative colitis. ?

Arrhythmias : Symptoms quite possibly from cardiac rhythm issues. Need to see cardiologist and probably have month long monitor to catch the problem. If no findings may have to look for more obscure causes related to vascular or neurological causes. Take care of yourself.

Palpitations: Since you note almost fainting(seeing black) & shortness of breath with your palpitations, there is a possibility that you could be having a serious arrhythmia when you feel palpitations or as well as having significant low blood pressure. I recommend a workup by a cardiologist. Studies to include EKG, outpatient heart monitoring, thyroid&anemia testing, echocardiogram,,treadmill stress test