Hi! Sorry to hear about that! I can only imagine how horrible it must be! When I first learned I was pregnant I went staright to buy "What to Expect When You're Expecting." They have an entire section for that. Apparently, constipation is common, but so is diarrhea, but if you use the bathroom like you always have, then that's normal too! Haha. A lot of things said the exact same thing, so I concluded that everything is normal! I'm 29 weeks and so far, I've been pretty normal.
Check out this website, it might help!
It could be pregnancy-related or it might not be - it could be something like a bug that you picked it.
Since you are so early into the pregnancy and it happened since 7DPO my personal opinion is that its not pregnancy-related because at 7DPO you would have such incredibly low levels of HCG in your system (if anything above non-pregnant levels since fertilized egg may not have even implanted yet) that its not likely you would experience such profound "pregnancy symptoms".
yeah that was my thought also. 7DPO is way to early to have symptoms. Although the breast tenderness started at 9DPO or I o'd earlier than I thought. I did feel cramping that day I was hoping was implantation.