I met a guy online last month and we hit it off.
No, I'm afraid it doesn't sound like he is.
Sorry, but if he was into you he would not have left you hanging and he would not be ignoring you.
It hasn't been that long since you haven't heard from him, really... I'm not sure what happened. It is possible he just lost interest and tried to fade out. That happens often in situations like this.
Save yourself some dignity and anguish and stop trying to get in touch with him. Unless he had a medical emergency (and he'd let you know at some point if this were the case - You wouldn't have to be the one to get in touch with him), let this drop and move your life forward. You should be doing this anyway. If something catastrophic happened in his life, let him sort it out and be the one to call you. Acting needy/desperate is only going to hurt you.