Nope, I didn't miss it. If your estradiol was 8 before starting TRT, and now that you've been on TRT even for a few days, if you're now having symptoms that might suggest issues with estradiol level, still it would be wise to get tested (again) before starting A-dex.
You started out with low T and low E2. Okay... so you start TRT. Now your T is through the roof (with a dose like the one you're on I wouldn't doubt seeing TT @ 1500+) and your E2 is starting to balance its self. Meaning your E2 is now through the roof also... that's my bet. I'm really amazed at your Doc prescribing that much T to you.
You need blood tests to be sure though. If your nipple is itchy (not your imagination), then *I* would probably call my doctor... stop applying the cream... and start taking nolvadex immediately. That's what *I* would do. Make sure you clear it with your doctor though... If the Doc is only available M-F then call him/her first thing in the morning and give your concerns.
Having too high of E2 is far more dangerous in my opinion than too low. Too low will kill your sex drive and cause you to feel terrible... but you wont get gyno, and if you stop taking arimidex your E2 will balance back out naturally to your (hopefully) now lower T levels.
I am not a doctor. Do not take what I say as medical advice.