I am sorry that it has taken so long to respond to your questions. By now you have probably already seen your breast specialist. Were you able to find answers to any of your questions there?
IGM is thought to possibly be autoimmune in nature. My opinion is that it is. A lot of autoimmune diseases seem to occur together, so it makes sense that you would have more than one. There are other women on this forum who have other autoimmune diseases also.
I don't know whether having other autoimmune diseases could effect your chances of getting rid of IGM.
Are you taking medications? Some of the medications used to treat Rheumatoid Arthritis are the same as those used to treat IGM. I don't know anything about Hashimotos Disease. Have you tried changing your diet to manage your symptoms?
So sorry that I haven't been on in a while. The holidays are going by quickly. My GM is very much under control. My meds are doing what they need to do. Hopefully you are seeing a Rheumatologist for your Arthritis, and you can speak to him about your GM. Breast Surgeons mean well...but I believe they see too much cancer...and removal of cancerous tissue is first and formost in their minds. A Rheumatologist can treat all your autoimmune diseases together. I think they have a good handle on the drugs available, and how to use them. I also think they will be willing to work with you if you choose to go a more natural route.
Blessings to you on this holiday, and I hope you can hug your 4 year old soon.