My crown fell out a long time ago, and I feel a lot of throbbing pain there now. What's the worst that can happen?

My dental crown on my upper left tooth fellout over a year ago. There's a big gap/hole in my tooth now. I've been feeling alot of pain there,especially when I bite down on it and eat. The reason why I haven't seen a dentist promptly is because I also suffer from agoraphobia which makes it hard for me to leave my house. It now feels swollen,and at times I feel a bit of a sore throat. What should I do?? I am actually thinking about calling an emergency dentist tonight. I am on Medi-Cal.