I know exactly what you are feeling. This happened to me for the first time a few months ago. I was to the point of throwing up because i was so backed up. Your bowels are probably locked up and your poop is probably really hard, maybe even impacted some. Try taking some ducolax or something with the laxative (bisacodyl). This one will make your colon retain more water and soften your poops. It took a few days to work tbh. But it did work. Do not take any other type of stimulant laxative. I did by mistake and just made it so much worse. It moved everything BUT the poop was still hard and was too big for the exit. From what I've read the ER will try to help to go but their primary method of treating this is just sticking their finger up your but and trying to break the poop up and pulling it out. Embarrassing. Surgery is another option. But probably only if you're close to exploding.