Oo normal lang yan, mama! Maraming first-time moms na nakakaranas ng itching around 18 weeks kasi lumalaki na ang belly at dumudugo ang skin, plus ang hormones mo ay nag-aayos pa rin. A few of my mum friends nag-complain din dito, especially pagod work or humid weather talaga worse. Para sa 4D ultrasound near Marikina, I'd suggest asking your OB for referrals kasi they usually know the best clinics with good machines, maraming magagandang centers in that area pero mas safe if rec ng doctor mo talaga. Congrats sa pregnancy, and don't worry, the itching usually lessens after a few weeks!