Can u sue a hospital for negligence? my 21 yr old brother has went the ER numerous times in pain & breathing?

This hospital treated us so nasty. My brother has a history of anxiety attacks. He was taken to the ER by Ambulance and was in extreme pain, the hospital wont even bother looking at him and assume its an anxiety attack & kick him right back out to the waiting room & give him his discharge papers right away without the doctor even seeing him. The only time the looked at him was the first few times he came to the ER and never again after diagnosing him with anxiety attacks. The last time he was at the ER a 4-5 months ago, he was literally screaming in pain and nurses not knowing I was his sister standing outside his room were making fun of him and nasty remarks. They completely ignored him, he was screaming in pain and having shortness of breath. He overheard some of the staff making fun of him & asked me to take him home right away before anyone discharged him. Several weeks pass by, and his symptoms got a lot worth, any little food he would eat would put him in pain, shortness of breath, blood in his stools shortly after. He is anorexic now and the bleeding got worth that he could taste blood. I am currently a nursing student & know a few things about GI bleeds. The other day I smelled an Internal GI bleed, the same smell my teacher made me smell on a patient with GI bleed. I know what an internal Gl bleed smells like because my past patients. The thing the local ER we go to treat us like crab, the wont even look at my brother, the last few times the discharged a few minutes after his arrival and did not bother to check anything but say its an anxiety attack. I know anxiety attacks don't make you bleed from both ends of your body. He bleeding with every bowel movement and constantly having shortness of breath. eating the smallest amount of food will give him pain and breathing problems. My brother now is so traumatized by that hospital that he refuses to go to the ER, I was even so disgusted with the way they treated him that I felt a lot of stress for weeks. My brother is so young, & he is home 24/7 not able even eat or move much because of his pain. I am so afraid he will die on me because this hospital is so nasty & wont even take 5 minutes to listen, instead the make fun of you & talk behind your back like its no big deal. Is anything I can do about this? I am so mad and disgusted with the way they ignored my brother & now it looks like he has major health problem. I am planning to take him to a hospital that is over and hour away but he is so weak im not sure he can handle it. Since he has no income now he would qualify for medcaid