undiagnosed and worried

My mother just passed away a month ago from vaginal cancer at 83.  Of course this has been a very stessful and sad time for me.  I have been having my own unexplained symptoms for about 2 months now and have been to 3 doctors.   GP did a DRE when I had first symptoms of pain and burning around anus and change in bowl movements, she did not see or feel anything abnormal nor see any sign of hemmoroids, suggested sitz baths and if that did not help she would recommend a specialist. Saw colorectal surgeon  3 weeks later, (1 week after my mother's death) with same symptoms. He did another DRE and and anoscopy, he did not see or feel anything abnormal - I told him I would like to get a colonoscopy which he felt I was not necessary since he saw nothing but would refer me since I was having pain. Met with gastrointerologist the next week told him all of my symptoms and he performed another DRE and anoscopy, all he saw was a little irritation on the outside of my anus, but nothing else. He perscriibed a compound ointment with Diltiaszem, to help calm the area, apparently they give this for anal fissures although he did not say that I had one. Ointment seemed to help a little but not much.  I had the colonoscopy on Friday 9/30 and that also showed/found nothing to indicate anal cancer. Needless to say I know that all of the Dr's think that my symptoms are all stress related due to my mother's illness/death which I disclosed to each of them and I know that stress can cause many things in the body but I am still having the same pains which has become more intense as the weeks go by. Feels like there is a knot that I am sitting on, lots of pressure almost feels like a pinching/burning sensation, and pain on vaginal wall. In addition I am now having pain in my under arms.  My gastrointerologist said the next step should be a pelvic MRI which I hope to get this week.

The not knowing is starting to make me feel like I'm going crazy.  I have read here and on other sites that this can be diffficult to diagnose. I also realize that many Dr's have not  seen anal cancer before because it is so rare.  My GI said he has only seen it 1 time in his career.  I really don't know what to do if the MRI does not give me answers- I don't know if this is a difinitive test or if I have to just keep going to differnet doctors - I pray that it is not cancer but I am so scared that if it is cancer and they don't figure it out soon it will spread.  Any advice you can give is greatly appreciated.