I'm nervous!

I had a misscariage in January 24th and ever since then trying to get pregnant again. Finally 3 days ago I took a pregnancy test and it was positive. I am super excited and happy but today I woke up feeling weird I have like cramping going on.... I don't know if I'm just overreacting because of the misscariage or what? I called my obgyn but they said to go straight to the ER. What should I do?! I'm worried... And feel fausterated.... According to my LMP I am 4W 3Days.