YIKES!!! I don't think I want to take morphine ever again!?

I recently had surgery, and was prescribed morphine for pain. Well, like a trooper, I tried to tough it out as best I could (addiction run rampant in my family), well, this morning, I couldn't take it anymore, so I decided, well, I'll just cut one up int 1/4's. I took one of 1/4's and for about the first 15 min. I felt nothing, so I thought well, whatever, I'm not taking anymore than that. 30 min. later, I started feeling a strange burning sensation up in my rib cage (the soft part where they do the chest compressions), and then this strange spasming in the same spot started. Now, I've called my doctor, and I'm just waiting for him to call back, but while I wait, I wanted to know if anyone else has gone through this and what he** is it??? I tried to vomit the pill back up, with no luck, but it seems like the only way to make the pain go away, is the gagging reflex when my stomach sucks in, but that only last about 5 minutes before the pain comes back. I can breathe fine, as long as I don't take deep breaths, but this pain is moving into my shoulders (like a gall bladder attack but in both shoulders). Is this an allergic reaction? I have learned my lesson and I'm going to take the pills back to the pharmacist. How do I make the pain go away? I would cry but that would probably make the pain worse.