Alhamdulillah baby okay! Honestly dengan fibroids sebesar tu at 18 weeks, rasa lenguh dan sakit perut memang common because your uterus sedang expand and the fibroids boleh irritate the ligaments around, a few of my mum friends with fibroids during pregnancy also complained pasal similar discomfort, especially when walking or lying down. Best thing is rest when you can, try pelvic support belt (helped one of my friends a lot), stay hydrated, and avoid heavy lifting, tapi since you have multiple fibroids, definitely check in with your doctor about the specific pain pattern, especially if it gets sharp or constant, just to make sure everything is managing well with your situation.