Middle back pain and right side pain

I am a 21 year old healthy female. Over a week ago I stepped out of my car and had sudden unbearable pain back, it knocked the wind out of me and took me about two minutes to catch my breath. The pain did not become less painful so I went to the E.R. where they took and xray and a urine sample. They found a small amount of blood in my urine but it not think it was enough for further evaluation. They sent me home with 3 different types of pain killers. My pain has decreased a little but i still have sharp pains when taking a deep breath and stabbing pains under my ribs throughout the day. The pain killers only make me tired and do not stop the pain. They said it could be muscle pain, but when i touch my back where the pain is it does not increase. When the pain started I did not do any exercise or lift anything heavy. Should i go seek more medical attention, or could it still be muscle pain?

[kait328]

I also have no appetite.