I have tried resting because I am very active but my doctor said it was common but she wasn't sure since my baby should be bigger by now. I have been also watching my diet heavily. Maybe it is just some spotting, my bladder and other has been funky lately.
I had bright red blood(period like) during my 16th week, and I immediately went to the doctor. Turned out it was a blood clot outside of uterus called hematoma. Safe if I bed rest but I'm not supposed to be moving around too much. Your spotting maybe the same or similar case. My best friend had spotting but she gave birth to a healthy girl at a full term. If you're being active, it's probably good to rest. Ask people around you to help do all the house work. I hope you don't have to work. I'd suggest you to see your doctor if u out continue to bleed.