Worried about cancer coming back

I am playing a waiting game and was just wondering how others in a similar situation are coping.
I was diagnosed with breast cancer in 2012 at 38 with three kids under six so it was tough but we got through it. Obviously I had to leave work while I was sick but returned eventually. Things didn't work out and I went ahead with another surgery this past January to sort out pain in my shoulder that I was experiencing due to the first surgery. All was going great. I was offered an excellent opportunity to go back to a really exciting position, one where I could work from home and set my own hours so we booked a holiday to disney world with the kids as one last hoorah! Three days before we left I was in agony with cramps and thought my appendix or something was about to explode so was brought to my GP. He sent me to hospital where I was scanned straight away. The results were not back before I left for holidays which is a good thing. I felt much better after our break and got the email about the new job when I got back so made an appointment to go see my GP about returning to work. I left totally deflated. Those scans showed that there is thickening of the lining of my womb and so I need to go for further tests and will not be certified fit to go back to work after all. I am on tamoxifen following breast cancer and this is something that I have been told to watch out for because apparently it can lead to cancer of the uterus. I'm trying not to freak out. Life goes on with a busy weekend ahead with the kids soccer, basketball, hurling, parties etc etc but all the while this is in the back of my mind. I'd like to know if anyone else with a history of breast cancer has had similar issues and what were the next steps.