Hi, sorry you're feeling horrible- I know what it's like, i've slipped two discs in my lower back, and it's a party, believe me.
The hormone I think you are referring to is called "relaxin" (pretty appropriate huh) it allowes ligaments to stretch to allow you to give birth, but yuor friend is right, it can cause problems, you are ore prone to injury, because you are looser.
I think what might be causing you problems might be the baby's head maybe having dropped into the pelvic cavity already. This happens with first pregnancies alot- 2nd and subsequent babies sometimes don't move down until you are in labour, but first babies get ready early for some reason.
Anyway, the extra pressure caused by the babies wieght on your pelvis can cause pelvic, lower back and leg pain simular to what you are describing. It can also cause nerve pain and pins and needles. It's is normal, but damn uncomfortable- it doesn't happen to everyone, but it is not uncommon.
It might be easier to make yourself more comfortable if you get yourself into a position where the baby is not pressing down on the pelvis- getting down on all fours for example, leaning forward slightly- or creative use of pillows in bed. What you want to try and do is use gravity to relive the pressure.
You will need to rest, and avoid strenuous excercise, it is ok to take paracetamol- but discuss with you doctor first.
I hope this helps you, at least maybe to find your self a comfy postition to rest in from time to time.
Take care, and take it easy- i'll bet your baby comes a little early, if he or she has moved down already, so the end might be in sight.
Xx el.