I was going to say that it appears that their connection is not symmetrical, because Quirrell was able to track down Harry during the troll event. Further research seemed to reduce this likelihood, however.

Quirrell started burning through the substance of Hogwarts once he realized that Harry had found the troll. He didn't know that the two had met until he read Harry's emotions. That he did not realize that they were getting closer before means that he wasn't tracking both the troll and Harry. I was going to say that it appears clear that Quirrell was tracking Harry (almost certainly via link), because he is not fool enough to leave his magic on his weapon, but not only did he strengthen the troll (and thus must have a method of covering his tracks) but also there is this:

The Defense Professor had felt the boy's horror, through the link that existed between the two of them, the resonance in their magic; and he had realized that the boy had sought the troll and found it.

That does not seem to imply that he could feel Harry zipping all over the place, because I would expect Quirrell, being able to read Harry's emotions in the Great Hall and since, to correctly deduce where Harry was going if he started moving in a hurry. That implies that what he was tracking was indeed the troll, and so reduces the likelihood that he could track Harry with the link.

Though it is still clear that the resonance is not wholly symmetrical, as Harry lacks the emotion-reading aspect.

If he does get even a vague sense of doom at large distances, then he could have triangulated regardless, first with the second set of emotions that would have popped up an hour ago, then with the current ones from a different starting location.