I'm not at such an early stage as you are, but I was drawn to your post by the mention of her2 positive. I was diagnosed way back in 1990 and with secondaries in 2002 and have been on herceptin since 2004. It wasn't around at the time of my original diagnosis! but has been a lifesaver for me these many years. Have you mentioned to your oncologist that you have these pains in your upper and lower back? If not I think you would be wise to do so and they should do a bone scan. It maybe that you have done so and already have scans planned as part of the usual baseline scans to get an overall picture of what is happening in your body. It's an awful lot to take in when we are first diagnosed and I hope you will find it a help joining in the relevant parts of the forum.
Welcome to the BCC Forum. I'm sorry you're going through such a tough time. I'm sure other members will soon be along to offer some support.
You might also find it helpful to give our helpline a call to talk things over. They can offer practical information and emotional support. Calls are free and confidential. The opening times are 9-5 on weekdays and 10-2 on Saturdays. The number is 0808 800 6000
Very best wishes