Hi, Onspiritualpath,
I agree with the others about going back to a doctor, and being checked out. I have pulsatile tinnitus, too; I've had it for over four years now. It started suddenly, and I first noticed it at night, just like you did.
Just to be sure, is your pulsating sound definitely in exact sync with your heartbeat? You can tell by taking your pulse, and counting the beats you feel in your wrist for one minute. If they are the same as the pulsating in your ear, that's pulsating tinnitus. If not, it could be tensor tympani syndrome, or something similar.
If it doesn't go away soon, it's best to have it checked out. The doctor may suggest an MRI or CT scan of the area. The first test I had was a CT scan of the temporal bone, to be sure there was no bone thinning in the area of the ear that could be causing me to hear the sound. Then, later, I had an MRI and MRA (with contrast) of the head, to see if there could be a tumor or fistula. I didn't have anything unusual, and to date, I haven't found the cause. However, mine has gotten calmer and easier to live with.
Many ENT doctors don't know a lot about pulsatile tinnitus, so if you go to one and don't get any answers, then you might want to check with a neurologist or neurotologist, who might have more understanding of what your condition is.
Good luck, and keep us posted on how you're doing!