hello everyone. i was wondering if it was possible to sue a

hello everyone. i was wondering if it was possible to sue a health insurance company. due to this reason: i have been diagnoised with lupus for about 5 years now and have been on a medication which was working fine. after a couple of years the insurance company decided that it was too expensive and refused to pay for it. they gave me no advanced notification. my doctor explained to them that this medicine was a necessity. they still refused to pay for it. i couldnt afford the medine out of pocket so i had to change medications. when i stopped taking the medicine i became very ill and was hospitalized for months. my sicknessi has became worse since then.i have began having seizures and was forced to withdraw from school. and now my family and i are struggling with financial issues. is there anything that i can do?