I have a burst blood vessel in my left eye which is neither sore of itchy but does seem 2 b spreading. what do u think it could b?

A burst blood vessel: If you are seeing red in the white of your eye (/sclera), this is a subconjunctival hematoma (=bruise), and is normal / harmless, but since is under a clear layer and not skin, looks very prominent (and scary). Often appear w/pressure (cough / sneeze / bearing down / lifting). Unless on blood thinners, they go away on own & are self-limited.

Exactly what u think: A burst blood vessel on the eye (subconjunctival hemorrhage) looks horrible, but is not visually threatening. It's an eye-bruise that can spread out and look worse before it gets better. Try to minimize the causes: eyerubbing, valsalva maneuvers (e.g., heavy lifting, coughing, sneezing, straining with constipation), and refrain from bloodthinners if possible (nsaids, vit e, st. John's wort..).

Subconjunctival : Hemorrhage is almost certainly what you have. I agree with what has been said. These look scary but are completely harmless. Nothing needs to be, or should be, done. These take care of themselves.