Is this anxiety?

Ok, im a master at this. But the pulsing pain raises an eyebrow. First of all there are many reasons for anxeity without external stimuli. The fact that you are hyper aware of your bodily sensations shows that your body is stuck in fight or flight mode (anxiety). Most anxiety issues can be directly linked to nutritional deficiencies and poor lifestyle choices. Good news is that its completely curable. I suggest you eat very healthy and take a good multivitamin/mineral supplement to feel in the gaps, plenty fruits, proteins and fats. You should google "Deficiencies that cause anxeity" and you'll be surprised. The pulsing in your head can be migranes, which you can also link the cause in nutritional deficiencies. I suggest a healthy diet, proper sleep hygiene, moderate exercise, and stress reliveiving activities. Please take my advice. If this lifestlye change does not fix your problem and the pulsing persists, you could have a more serious problem on  your hands such as a brain tumor, weak arterial walls in the brain that can rupture causing stroke. Please do not be frightened as this would be a very rare case for an 18 yr old. All else fails, visit a doctor, a get an MRI of your noggin and find the results. But I promise once your live your life healthy in every way, your symptoms will subside until they are non existent. Good luck, you'll make it! :)

P.s. anxiety is very good at playing tricks in your head, it can definitly manifest itself through bodily sensations. such has muscle twitches, heart palpitations, head aches. Even digestive problems!