I went to the emergency room this morning , severe lower abdomenal pain that started a little over 24 hours ago.

the pain is on my right side theres a twitching thats intermittent.
At the ER the ran a ct scan and ultrasound looked at my apendix and gallbladder
the doctor said those things looked fine but i still have the problem i'm in alot of pain it feels like the right side of my belly is swollen it hurts me to twist, situp even hurts when i lay down due to my insides being pulled in from gravity or whatever.
its a sharp stabbing pain. i will admit that i feel like maybe im a little backed up
but the dr said the ultrasound didnt look too bad as far as my colon being overfull.
i don't know if anyone can help me or not i'm just scared because dr say that im ok but i truly am not i wish things were fine.i gotta go back to work tomorrow and i can barely walk, i have noticed if i sit upright it hurts less its the owrst when laying flat and trying to sit up. could this maybe be a strained muscle?
remember the pain does spread to my right side in addition to the right side of my stomach.
it honestly feels like a knot in the right side of my ab that whole area feels swollen and not normal. i am not one of those people that fake illnesses or anything it really truly hurts and scared doctor has no idea. on a sidenote i tried some magnesium citrate i think its called to attempt to get things flowing again and within 30-45 mins i vomitted it up. i have been able to hold down foood since then. but if anyone has any ideas please help me out.