Healthy 19yo. Never had headaches but now get the frequently. Is it likely that it is something fatal? I had a baby 5 months ago.

Unlikely fatal. Usually unlikely to be fatal in young age. Did u have epidural at the time of delievery sometime that could be cause of headache due to dural puncture. Get evaluated.
This msy be . From your spinal anesthesia or a totally separate entity.Have your pcp check you thoroughly and refer to a specialist neuro as needed.