welcome to HCM,
congratulations for your pregnancy
since you are having placenta previa
( low lying placenta) , painless fresh bleeding is the most common symptom of this condition.
you are presently in the first trimester of pregnancy, there are chances of the placenta shifting upwards in the next trimester.
presently you should rest in bed , prevent much walking and working and keep your mind at peace and out of all stress
any heavy bleeding you should immediately go to the hospital for further care.
headache may be due to the stress you are facing.
take bed rest
and take good care of your self.
may god bless you.