Bad headaches from a toothache?

These past few days I've been having really bad toothaches, which then triggers a headache. A few months ago I had fillings done on my right top and bottom molars, and these are the teeth that are bothering me. It's kind of weird, they felt fine all up until a few days ago.. They are also extremely sensitive to heat and cold, which is also driving me crazy. What could be causing this? Is it anything I should be worried about?