Well, I have had tinnitus in various forms over the years.
I don't know if I have allergies but I find that my tinnitus is definitevely
worst during spring and maybe fall as well.
I suspect it is related to allergies.
As for pulsatile tinnitus (hearing blood/heart through in the ears at nigh
especially) I also have that but I find that it's gotten worst this winter.
You wonder if it may be related to your periods right?
I may shed some light on this for you as I've been doing some research on
this myself.
I went to the doctor to get a pap smear and was told that I was severly
anemic and that I had a large fibroid tumor in my uterus.  I loose a lot of
blood each month during my period because of it.
Lately, I found that I could not only hear the blood rushing through my ears
but also feel it.  I complained to the doctor about this and she sent me to
ENT.
After this, I searched for anemia symptoms and there it was: pulsatile
tinnitus.
I suggest you do the same...but to save you some time here's what I found
out if you are interrested.
Anemia symptoms:
pulsatile tinnitus
restless legs syndrom
rapid heart rate, out of breath easily
pica = the desire to eat unually crunchy stuff....for me I wanted to eat
nuts and ice just for the crunchiness.
paleness of skin, lips and nail bed.
frontal headaches.
I had all of these symptoms.

Get your iron checked, I feel much better since taking supplements.
Don't just get supplements, get checked.