Should I go to ER? What do you think is wrong?

I'm a 30 yr old female. For 4 weeks I've had severe constipation. It started with feeling like something was stuck in my mid-right abdomen. Felt bloated and only had 3 very small BMs since then. 2 days ago the pain got worse. It's in my mid abdomen and is a very sharp burning pain. Sometimes it feels like a burning sensation spreads into my entire abdomen. It's constant and does not go away. Been there for 4 weeks and getting worse. Since last night I would have a sharp pain in my lower right abdomen and it's tender there also. Pain radiates to my left shoulder also. I haven't been able to eat in 3 days and have lost some weight. I feel full after 3 bites and it makes my stomach hurt worse. X ray a week ago showed large amounts of stool. I've had good BMs today finally. I can't even drink water. Pain is sharp and burning and not like typical gut or gas pain. I've belched a lot even on empty stomach. I've heard that could be hiatal hernia or ulcer. I've also thought possible pancreatitis or appendicitis. I've had a fever off and on. VERY bad nausea but don't vomit. Getting weak and tired from not being about to eat. I don't have insurance to go to a specialist. If it's serious I can't wait for weeks either. What's possiblity of exploratory surgery if labs are normal? I'm tired of this pain. Haven't slept in 2 nights. Go to ER? What do you think it could be? I don't have acid reflux. Thanks.