Wow, you have a lot on your plate right now!
The heart flutters is called palpitations. The term refers to the ability to feel you heart beating fast or irregularly. It is common for many people and the causes vary. Your other symptoms sound like they are anxiety
related. Someone else mentioned panic attacks which are definitely a possibility. As for your symptoms occurring at night, it may also be happening during the day but you are unaware of it. When we sit down and try to relax, we become more aware of our surroundings and what is going on with our bodies.
I strongly recommend seeing your family doctor. He can better evaluate you as an individual and help determine the best treatment. A low dose anti-depressant for a few months may do you some good. You may say that you don't feel depressed, but there are many uses for these drugs.
Best of Luck