As other say, yes, you and your son must see this psychiatrist immediately, and if this one doesn't click with your son, find another one. You don't mention whether there is a husband or significant other in the picture but if there is, he too must be 100 percent on board with getting help and he needs to be there by your side to hear what the doctors say. Imaginary friends, great. Destructive and especially self-harming behavior--a cry for help.
One red flag that concerns me isn't about your son. It's about you. You write, "I am hoping he is just very imaginative and creative." He may be both those things AND also still need serious professional help. You and his dad need to be very open and receptive and willing to learn if the psychiatrist finds your son has problems that must be dealt with through therapy, medication, behavioral changes, etc. Please be sure you're not, in the back of your mind, trying to convince yourself "He's just creative" while a doctor is simultaneoulsy saying, "He's ill."
I've seen this happen and the kid picks up on the fact that mom and dad are not fully on board with the doctor and will use that to wriggle out of treatment because he knows mom and dad are not totally going to enforce it. I'm not saying you'll do this, I just know it's a risk that is there if the parents hope, hope, hope their child is "just acting out" or "just in a phase" or "just creative." You already know his behavior's not normal, as you wrote, so you're most of the way there.
You are doing totally the right thing to have him seen, but be aware that this may just be the beginning of years of therapy and other interventions. If it's not -- fantastic. If it is -- be ready to accept that.
Please update us here. Your son is going to get good help!