My boyfriend is experiencing the same thing except his is on the right mostly but all on his waist and no hives. His father wont take him to the hospital and claims that he is making a joke. I'm not sure what you would have, but try looking it up. I'm in school right now, but I've been looking up a lot of things to figure it out. Try searching up pain in the left waist area, then go and ask your doctor with a list of things you found on whether or not that is whats wrong with you. I'm doing that and once I'm home I'm going to ask him if maybe these things could be happening to him on my list. I hope you do find out.