Please help!

I went 2 the Dr a few months back Bc my upper/shoulder was hurting. He did a xray and found what he thought was a bone tumor. I then went for a Ct scan, bone scan and a mri. They did a biopsy and still isn't sure what is is. I will have surgery and they remove it and do another biopsy. The Dr said he thinks it not cancer but the Dr that did the MRI biopsy said its took over my marrow in the top of my arm. I cant get a straight answer. I'm so worried any ideas?