Is it ok?

My husband and I have an older dog. We did not ask for him, we pretty much inherited him when my father in law passed away a year ago. My mother in law refused to take him and with him being older we didn't want him to go to the pound because he most likely would have been put down. He has 3 tumors. We do not know if they are cancerous or not. We were going to have them removed Wednesday, but decided I needed to see a doctor more first. We have been taking him to the vet and putting his needs above mine for months now. My family was mad at me for putting his needs above my own because they are worried about me. We will be taking him for his surgery next month. But now my MIL is mad at me for not taking him in this Wednesday. Also, she hasn't lifted a finger to help us with him or anything. But she is throwing a fit that I will be receiving care first. Is it ok for me to go in first this time or should I just take him and wait for me to go again? I haven't had a period in 5 months and have had cramps and stuff pretty bad lately and other issues.