Soft tissue sarcoma to Osteosarcoma

Hi. I was a former cancer survivor of 7 years until recently, I went on one of my normal routine check ups and once I did my xrays, my doctor told me a small legion appeared on my right shoulder. My first cancer was under my right arm, so after doing a biopsy (no good results) and then a surgery, my doctors still weren't sure of what that legion was. So after sending my results through 5 other specialists, including the Mayo Clinic, I finally got an answer: Osteosarcoma. It was so out of the blue because even though I knew it was a possibility, it had been 7 years. that I had been in remission. So a new cancer, and up to 12 months of chemo. Doctors consider me lucky because the cancer was so early on, it was the reason why they took so long to diagnosed. My oncologist also told me it was most likely caused by my radiation therapy from my previous diagnosis. I'm still in shock, going through the motions...and I already went through my first round and lost my hair. I'm just looking for other people who can relate to this type of situation and hopefully can answer some questions about Osteosarcoma.