lung cancer & breast cancer

My 69 yr old mom was diagnosed with Invasive Lobular Carcinoma of the left breast and had total mastectomy of that breast in Mid Oct. 11 Lymph nodes tested positive for cancer. She had PET scan on 11/06. Was found to have no hot spots EXCEPT for a very small spot on her lung. So...next came the CAT scan, that was 11/11. They did see a tumor...unknown if its cancer but we assume it will be...but, unknown to everyone...they also saw blood clots!! She had absolutly NO leg pain at any time. She HAS been complaining of shortness of breath JUST since the surgery. She asked both her surgeon, last week, and her Oncologist..and they both kind of just pushed it aside. Well, nobody expected the clots. They kept asking her if shes had leg pain, and shes had none. First...can you tell me..do blood clots START in the lungs?? Is it related to cancer?? She is complicated...they didnt want to treat the clots till they did a lung biopsy. What a mess, huh? And VERY VERY scary.
She had the lung biopsy yesterday. They had to go in thru her back ( is this the usual way?) and said its a very, very tiny spot,tumor,mass, whatever its called. Its near a blood vessel, so they werent sure they would be able to get at it easily, but said they did get a good piece of it. The Oncologist and the radiologist are still not certain its cancerous, but we are.
They immediatly sent her to the "blood clot" clinic, and shes on MEGA doses now of blood thinners...she takes I think its Coumadin ...and she has injections that we give her, or, she gives herself 2 times a day at home.
They sent her home! I guess thats common? But scary for us.
My parents live in rural area...appx 40 minutes away from a hospital, and appx 20 min from a 911 phone call ambulance service. Im up here with them, to help out..

They travel to and from their Oncologist...so they are doctoring in a major city. She goes tomorrow to find out the results of the biopsy and to get another shot of blood thinner and have a blood test.

What is the prognosis for someone  that has a tiny mass in the lung---and has ILC as well? She hasnt even started treatment yet. We WERE very encouraged at first...when we found that the PET scan showed just the tiny spot on the lung....but now...not so sure.........

Help...any answers to the questions Ive asked above, would be so helpful. Cancer is so new to us...no one in the family has ever had it...

thank you...