You need to go to an oral surgeon.

You probably have a furcation. That is caused by bone loss around the saddle of two roots of the tooth that leaves sort of a huge upside down valley type pocket under the gum between the tooth and bone. It is way up there under the gum. Had one in 1999 and they did a root amputation, root canal, graft etc and the tooth is still in my head and good to go. I am surprised it lasted this long, but the surgery was $2500, plus a root canal, and I think I had a crown on that one too.

Now I have the exact same problem on the other side unfortunately.

If it is a furcation you will never be able to keep it clean.

You may be able to delay the surgery or having it pulled with a water pic with the pick pocket attachment or maybe even better yet Colloidal Silver in a syringe (no needle) if you can find a rubber tip and shove that up in there and give it a shot of colloidal silver every couple of days.

The anti biotics you get are about 25 cents worth of tetracycline and they charge me $39 per, and it does little good.

There is also a condition where you body attacks the tooth as if it is a foreign object. I forget what it is called, but pulling is the only cure for that.