Finasteride side effects after 5 days. Quit a week ago; extreme anxiety.

My first question is did your prescribing Dr take blood tests and review your hormone levels and DNA prior to prescribing this for you?
If not I would recommend seeing a hair loss specialist who will do this. There are a percentage of men for whom DHT blocking medications while preventing the imbalance in DHT that cause hair loss also causes an imbalance in other hormones which result in side effects.  These are easily prevented with knowledge.  You need the bloodwork to understand how your body will handle the medicines.  Note there are also now better alternatives to finasteride available too.
See a hair regrowth specialist who will review your DNA and bloodwork and prescribe the right medicines and dosing that is personalized for you rather than the "average" population.

You
described quite a few of issues that you feel were related to finasteride.  The most recent studies show that erectile
dysfunction is rare phenomenon.  The more
common side effect that is usually reported by patients is decreased sex drive
or libido and the chances of it is about 1.8%.

I am sorry you are having the sexual side effects listed. Various sexual side effects will occur in about 2% of men who take finasteride. They usually come on during the first 3 months and yours came on in the first week. You certainly need to stop finasteride and fortunately it has a short "half life" of about 6-8 hours. In other words about half of the finasteride in your system will be excreted during this time. It has been my experience  with my patients they usually return to normal with in 1- 2 weeks. I wish you the best! 

Sexual side effects from finasteride are very rare. It is almost unheard of for someone to experience what you describe as soon as three days after beginning treatment (and you are the first person in my 13 years of experience to report uncontrollable movements of the testicles, "hot flush", and "bloating"). Based on what you describe, and your level of anxiety, I would be willing to bet that you were all over the Internet reading up on finasteride either prior to taking the medication or immediately after filling the prescription. (Certainly, if you were not, and you were completely unaware of all the unsupported claims out there, I owe you an apology.)To be clear, there is no drug that has no side effects, but the much-feared side effects of finasteride are greatly overblown in Internet chat rooms, with no scientific studies to give credence to the high frequency of the claims. On the other hand, a large, randomized, controlled, prospective, double-blind study found that there was only about a 0.5% greater risk of decreased libido/ED compared to a placebo. It’s important to remember that up to 40% of men have ED by the age of 40, and that ED has myriad known causes: relationship stress, family stress, financial stress, job stress,  generalized anxiety, depression, and hypertension/diabetes/alcoholism/other drugs, to name the more common reasons. But finasteride has become a convenient scapegoat for many cases of sexual dysfunction, and more often than not the “side effects” are simply a self-fulfilling prophecy known as the "nocebo effect". (Your mind can be your own worst enemy — see link below.)It is also important to remember that the side effect of *not* taking finasteride is baldness. You might consider talking to your doctor about starting the drug again very gradually (e.g., 1/2 pill very third day and increasing from there). 

Sounds like a panic attack in that so many problems appeared.that appear unrelated.  All side effects should be gone in one to two weeks after stopping the medication but you might want to go back to see your doctor nevertheless.