I have a headache it's not like a migraine but its still there and this is the second day I've had…

I have a headache it's not like a migraine but its still there and this is the second day I've had it. I'm 19 weeks pregnant and I'm worried this could be bad for the baby is it bad for the baby? and what could cause this? I have been thinking a lot about the baby because I've had a miscarriage before this pregnancy and I'm just so worried and I've also had the flu shot already .