19 weeks back ache and aching stomach

Heya this is likely round ligament pain. Especially as it’s your second you’re abdominals are likely separated slightly still and this puts more pressure on the pelvic floor, lower back and fronts of your hips (ligaments there).

Try some yoga on YouTube. I really like Sarah Beth prenatal yoga for this and send hers to a lot of my clients too https://youtu.be/4NwQKXpWN_A?si=wedHyB5PXu0p1QVv

I struggle with this paid too, and I was told it was probably a combination of pelvic girdle pain and round ligament pain. I referred to women’s health physio and they gave me some exercises to help and also suggested a support band. Maybe see if you can get a referral to your local physio team?