35 almost 36 weeks having lower back pain that burns?

i have noticed that i have been having lots of lower back pain and it burns. i take Tylenol it will take a little bit of the pain away or walk around abit but when i go to stand up i fell so much pressure in by belly a braxton hix cont rations feeling. can i do anything for the pain? i have also noticed a clear liquid sometimes brown on my pad? did i loose my plug? when i went to the dr. last week she said i was a centimeter dilated and was thinning. have to go back friday.