I have been taking Diltiazem for almost a year resolving symptoms. Stopped taking 3 weeks ago as scared of Stevens Johnson Syndrome- likelihood?

Don't stop. Diltiazem is used to treat hypertension. It is a calcium channel blocker. Stevens-Johnson syndrome is an extremely rare side effect and if you've been taking it for a year, don't worry. And let your doctor know you stopped it.
Asking us questions. Please rewrite your question and include the specific symptoms that are causing you concern. We cannot guess at them.