What Causes Constant Headache While On Treatment For Pressure In Portal Veins?

I have been taking this med to reduce pressure in the Portal vein and help varices . Taken for 2 weeks so far ... I have had a constant headache..my whole head and neck throbbingand sore to touch head I had 2 days with blind spots and flashing lines and other visual disturbances, some days with nausea ,and I have had bloating and cramps and very loose stools , cold hands and feet