What do I do about these temper tantrums!?

My son is a year old and this past week has been having terrible temper tantrums. He slams his head against the ground and will also slap and punch himself in the face and the head. Sometimes he does this for no reason and I don't know why. Mostly it's when he doesn't get what he wants but sometimes he'll be fine and he'll just get down on his hands and knees and slam his head against the ground. I just don't understand! My family has told me to ignore him and he'll stop, especially if it hurts.... Well I've done that and he still hasn't stopped. It's gotten worse even. The other day he slammed his own head so hard on our wood floors that he had a bump on his forhead and it even turned into a small bruise. I don't know what to do. When My husband would acknowledge him and try to get him to stop he only did it harder. I'm not convinced that his doctor knows what they're talking about.... They told me to get on his level and explain not to do that and tell him firmly "no." He's only one year old, no more then that and I dont think he understands....He just fights it and as I said he does it harder when I pay him ANY attention... I'm extremely concerned and I don't want him hurting himself but i don't know how to get him to stop this.... I need advice from others who have been there or even ideas from people who haven't been. I've never dealt with a temper tantrum like this before so I'm at a loss. Please no rude comments. I can personally recall me doing this when I was younger and my mother told me to ignore him and he will eventually stop but I'm more concerned with him hurting himself in the meantime.