What does a ectopic pregnancy feels like

Kellie • Mother of three and currently ttc #4 due to health issues my chances are starting to shorten every day! Staying positive and wishing everyone lots of baby dust
Haven't had a ultrasound yet but i am having this pain that will not go away.. Im afraid that something is wrong. My doctor said i shouldnt worry to come in on may 16th but this pain wont go away. And its not no normal pain it almost feels like something is about to pop or like my fallopian tube is rubbing against something. I hate to keep running to this er but i cannot take this pain. Ive had a late miscarriage at 20 weeks nd this is exactly what ive felt like.. What should i do?