Any Advice?

I was diagnosed with Hashimotos Goiter in 1985 so I have been on Synthroid for a long time. In 1991 I developed Thyroid Cancer and had my thyroid surgically removed and had the Radioactive Iodine Treatment. I have been seeing my endocronologist yearly and recently every six months. Some of my blood tests indicated that there may be a problem. I had a ultrasound in early August and it looks like some growth. So I'm in the middle of the low-iodine diet and will be doing tests next week. I go in on Monday and Tuesday for the Thyrogen shots, take the RAI pill on Wednesday and then have the scan on Thursday. I'm hoping that I don't have surgery but I anticipate that I will. I am really apprehensive about all this. I've been through this before and know basically what to expect. My greatest fear is that I had breast cancer in 2003 and worry that this is all connected. I had DCIS and had a mastectomy and nothing more. I don't think it is related. Has anyone had this happen? Can you tell me more about the side effects of the Thyrogen? Last time I didn't do that but was off my meds and I'll never do that again. Any help would be appreciated.