In areas that are lit/plain i see a dark shadow that pulsates to my heart beat, it seemed like it had a circular shape at first but now it kind of seems like it has the shape of a vein. i also have bad pulsating tinnitus. i feel my heart beat too?

If you have visual symptoms and/ or headaches with severe pulsatile tinnitus, you should be seen by an otolaryngologist & investigated for possible intracranial hypertension or blood vessel abnormalities. Appropriate examination & testing will be ordered after your examination.

Could be ocular floaters which are harmless or something worse. I would see an eye Dr.