Sorry but if its that bad, you will need to see a dentist. My guess is that the long time off from not seeing a dentist may have resulted in a deep cavity. Only dental treatment will solve the problem at this point. You may want to find a dentist who can sedate you to help "knock you out" so you can get your treatment done comfortably.
I feel your pain!! I am in AGONY right now and just want to jump off a building lol. I went to the dentist today and I need a root canal. The dentist gave me an antibiotic to clear the infection which should make the pain stop. Don't be afraid of the dentist! Take an ipod or cell phone to listen to music too while you have it taken care of. You'll be just fine!
By the way, are you in the UK? If so, my husband says that you can take a paracetomol/ibuprofen combo pill available at Boots or any other pharmacy near you! Hope this helps! Don't do the mouthwash for now, it may only irritate your tooth further!