Ahhh mama, 30 weeks memang tough betul, bby pusing-pusing, perut penuh, susah nak tidur, I totally feel you lah. A few of my mum friends complained pasal breathing difficulties around this time juga, and most of them said it's because bby getting bigger, uterus pushing up towards the lungs, jadi rasa penuh and breathless. Try sleeping with extra pillows (atas kepala sikit, sebelah perut juga), and maybe boleh try side-sleeping, my one friend swears it helped her breathe better malam-malam. But because you're feeling dizzy and susah bernafas, better mention this to your doctor at your next checkup kay, just to be safe and make sure everything is okay!