So sorry you aren't feeling well. Hopefully you were able to get tamiflu right away.
Regarding the '5 year pill', are you talking about the one to lower estrogen levels? There are several. I don't know how long you've been taking it, but if you still feel like it's not agreeing with ou after a couple of months, please talk to your Oncologist and let him/her know. You can always be switched to a different one. I had that experience.
What pain are you having in your breast? Are you having follow up visits with your surgeon? If not, you should do that. I saw mine every couple of months for awhile. I don't remember if you had a lumpectomy or mastectomy, but either way, pain (should be minor) may be with you for quite some time. I still have twinges of pain after 5 years. It doesn't last long.