Scared

can someone please tell me if im over reacting. Went to the ER due to shortness of breath. I am currently 5 weeks 2 days doctors said they see the gestation sac which measures 5 w 2 d and HcG is 4289 however they sent me how with paper work that says blighted ovum. Which my doctors said would be too early to see any thing on ultrasound. Has anyone gone through this and at 6 week ultrasound everything was normal?