What Causes Headache And High Blood Pressure?

Major headache for 2 days (166/99 highest). Blood pressure was 163/96 at 3PM, but has gone to 146/88 now. Notice after meals, there is a spike. Will watch salt intake. Was just diagnosed with Stage 1 Hypertension in Nov. due to a stressful job. Left job in Dec. and have been doing well until beginning of March. Hypothyroidism and rapid weight gain. On hydrochlorthiazide 12.5mg and levothyroxine 0.025mg. Been keeping a log and headaches have been significant upon waking. I have been walking and cycling up until the last 2 days, due to headaches.