Going off the pill + other stuff…

I decided to go off the pill after my supply ran out last month. I had also forgotten to take the remaining pills over the last 3 or 4 days. My period came on time, I believe around Oct 18.
I was off the pill last year for a month or so, and noticed that it casued my next period to be about a week and a half late, but when it did come, it lasted for about 2 weeks.
I know that everyone is different with their reaction to going on/off the pill, but I was just wondering if anyone had an idea how common it is to have a delayed period after going off the pill? How common is it to get pregnant almost immediately after going off the pill? I was always under the impression that it took a few months to get it all out of your system.
Although I am now off the pill, my boyfriend and I are still practicing safe sex. There have been no broken or defective condoms to my knowledge.
I am not due for my next period for another 3 or 4 days, and given that we use condoms and that I was on the pill until recently, I don’t think the chances of my being pregnant are very high. I am certiainly not freaking out yet.
However, over the past week and a half or so I have been experiencing splitting headaches almost everyday like clockwork and always in the same spot in my head. About 3 days ago my nipples started hurting like mad… it feels like somone pinched them in a vice! They are also quite swollen looking (I have very small boobs so it is pretty noticable). I guess the best way to describe it is that it feels like my nipples are sunburnt… that really dull, throbbing, constant pain. Also, there has been about 2 days when I noticed a really rubbery, thick, slightly cloudy discharge when I went to the restroom. (Almost like a big glob of what rubber cement would look like after it started to harden, but was still jelly-like). It didn’t really smell like anything. I never have had discharge like that before… usually it is creamier (God, this sounds gross!). My lower back is usually in need of a good crack and aches quite frequently, but nowhere near as bad as it has been lately. I have been extrememly tired and exhausted no matter how much sleep I get, and have been pretty gassy in the evenings as well. No food aversions or cravings (well, nothing out of the ordinary at least), and no nausea.
I know the odds seem pretty unlikely, but I suppose anything is possible right? Although I know it is probably very unlikely, I can’t help but wonder, and it has been on my mind more and more lately. Almost like there is some little part of me that knows something is strange. Has anyone experienced anything like this and has any advice?

-Not freaking out… yet