Mines like this. Been doing yoga and stretching but now referred to physio
I suffer with a bad back anyway and have been particularly bad the last few weeks. Gentle cat cow stretches are a good one, as is lying on your back and twisting so your knees touch each side. If anything hurts- stop! I also found out if you ask your GP to refer you there is a pregnancy physio who generally have a wait time of a week or two rather than the usual NHS months and it is free rather than costing the world! Hope the pain eases up soon.
I got a bit of back pain and mentioned it to my midwife and she referred me to physio, got an online appointment next week. Agree cat and cow stretches are worth trying as Pilates teacher recommended that to me. Hope it eases for you!