Unknown bleeding in third trimester ?

32+1

Yesterday morning when I got home and went to change I seen a dime sized amount of dried brown blood in my underwear but wasn’t bleeding at all when I wiped or for the rest of the day. Today while at work towards the end of shift when I went to wipe I seen the bright red blood but couldn’t find anywhere I was scratched or anything. I only see maybe a pen tip amount when I wipe now and it’s only every one in a while so I’m not sure. Any ideas?