TMI brown spotting 5 weeks 1 day

I’m 5 weeks and 1 day. I’m spotting brown blood with very little Tissue like stuff not sure what it is. I was told by my doctor, bed rest for 7 days to help prevent miscarriage. I do have very mild cramps but only when I walk around. She did an ultra sound said my cervix was completely closed and the implantation was in the right spot. This will be my first pregnancy an I’m worried I’m having early signs of miscarriage. Has anyone had brown spot and have a heathy pregnancy ? Btw this is day two of brown spotting yesterday was very light and today it increased.