Uy, mamsh, please go see your doctor about this right away, headaches paired with nausea like that, especially on a schedule, needs proper checking kasi it can be a lot of things and you need to rule out what's really going on.
A few of us moms have dealt with similar stuff during pregnancy, and habang iba-iba ang causes (sometimes blood pressure, sometimes hormones), kailangan mo talaga ng professional to figure out yours specifically, walang guessing game dito. Huwag na mag-self-diagnose, bes; gawin lang agad yung check-up para ma-address nito ng tama at kumain ka ng maayos para sa baby. Sending you love!