I'm sorry your in such a horrible raging place right now.

I went through about 8 Doctors when I started have all kinds of problems. I was so frustrated that I wasn't being given a diagnosis, test after test after test. I am not kidding over the months I know at least a 100 vials of blood was taken for testing.

As for your grandmother making you so angry that you are kind of losing it and actually thinking of harming her over it ... Can you just not talk to her, Stay away from her, If she does ask you a question just ignore it and walk away, hang up the phone etc.

Regardless of second third or eighth opinion you know your body and if you feel something is wrong then follow through until you find the help you need..

I do think a Therapist could be helpful in many ways while your trying to manage your physical problems.

I hope you find some peace and inner balance