What are the signs i could be about to go into labour, even if its not today.?

Im three weeks away from my due date, so its probably nothing. But i just thought i would try find out a bit more as this is my first pregnancy and i don't really know what to expect. For the past few days i've been waking a lot in the night been overly hot, or having very strange dreams, and waking up hours before i normally do. Ive been feeling really tired and have been sleeping for around four hours in the day (could be due to restless nights). ive also been getting increased discharge. I have been getting a lot of aching in my lower back lower belly too. For the past couple hours i have been getting some pains in my stomach, in line with my hips.. its like a dull ache which is coming and going every few minutes, and for the past half an hour it has gotten more pain full. Like i said, im three weeks from my due date, so it could be nothing, but if anyone knows what it could be, let me know please :)