I am sorry to hear about your condition. With history of
clots in the lung previously, it is possible that new ones have come
up. It is also possible that there is an old clot which got dislodged and is causing symptoms. With headache, dizziness, blurring of vision etc there is a possibility that you have either a clot in brain or an aneurysm with bleed, or benign intracranial hypertension. I suggest you go to the ER for this so that you can get medical help. Take care!