What could be causing this? HEADACHES!

I am 18 weeks pregnant and ever since Saturday 21st I’ve had headaches day and night. Some nights it’s hard to sleep because my head is hurting so bad. Last night I finally got rid of the headache all throughout the night till about 10 am this morning my head started hurting again. I’ve checked my blood pressure and it’s not high yesterday I checked it 2 times and it was 120 over 70 and 116 over 70.

I checked it about 10 minutes ago and it was 111 over 78 so pretty normal.

I’ve tried cold compress, Tylenol, drinking water, showers nothing is working. Any advise what this may be? What may be causing this headache? I have no swelling so I feel like it’s not preeclampsia.