Can I take finasteride 1mg and a multivitamin on the same day at different times or do I have to stop taking the multivitamin?

You can take these at the same time. I suggest seeing a hair loss expert now to evaluate and go over your condition and test results and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

There are no issues in taking these together. One does not block the other and are therefore fine to take together. 

You can take finasteride and multivitamins at the same time. They do not interfer with each other and many people do just that