First off, let me say how glad I am the test results were good. Secondly, your boss is an idiot, and you should be glad to be rid of him/her. On your interview question, you should be open with them, and tell them you had a cancer scare, and your former boss didn’t like your having doctor appointments on short notice. You may find your interviewer very understanding and sympathetic. Lastly, you might contact your former employers HR department, and make sure they understand the issues. This could be very important when they check your references. I know you want to keep this stuff private, but it will help you greatly if you allowed people to know. They will empathize, and you will have an ally.