Lower back pain but doesnt feel like sciatica?!

Iv had sciatica pain for ages now and that usually feels like sharp pains and comes and goes but throughout last night and this morning i have been suffering with the most horrible lower back pain that is going into my hips, butt and sometimes down my thighs. Im having to sit with a pillow under my butt - it feels horrible. Baby girl is really low down today as well i feel movement really low down - like really low down! Its so painful! Like someone has been at me with a baseball bat , im randomly letting out a scream whilst walking to the bathroom or back and going up and down the stairs is just a big no no right now. Any advice on what this could be or isit just sciatica pain? Not round ligaments as i know how that feels all too well lol this is more like a bruised and achey feeling rather than a sharp pain. Im 27 weeks today btw. Thanks in advance ladies x