hello , i woke up this morning at 4am to find wet underwears and bed sheets. it was cold in the room and i felt like i had to urinate like usual, after i urinated i wiped and saw a few spots of blood on the paper , went to bed worried and waited to go again . i wiped and only 1 spot of blood size of a pin head. what can this be . never had this before , i have been experiencing lower back pain only at night when sleeping and i did have sex last night too..please help.