damage is only reversible when it's caught very early.
1)floss every time you eat. Every. Time.
2)brush *very softly*, with a soft brush, for 2-3 minutes, ideally every time you eat - but at least twice per day. flouride toothpaste pm and this awesome xylitol toothpaste am
3)am and pm routine: floss, waterpik, brush, in that order - do not rinse after brushing topical flouride toothpaste and mouthwashes are supported by the evidence.....flouride varnishes and flouridated water are not.
4)take 1000 IU vitamin D3 per 25 lbs body weight per day except on the days you're able to get midday, unprotected, full body SUMMER sun to the point just before burning. there is good evidence that sufficient D3 halts production of new cavities.
5)take a Carlson k2 daily for a month then twice weekly after that. take one of these Natto based K2 the other days. Sufficient K essentially insures that calcium ends up in bones and teeth rather than soft tissues.
6)note that this diet (and any paleolithic diet) is not meat centered but produce centered. Eat mostly vegetables. A lot of raw and lightly cooked veggies. Your gums and bones need the veggies as much as they need the d3, zinc, magnesium and protein.
7)get 400-1000 mg magnesium per day and 500-1000 mg calcium per day....more is not better. experiment to see what works best for you. Higher/optimal vitamin D intakes generally mean lower calcium intakes are required.
8)dental care may be available at a public health department in your area or at a university dental school or college with a dental hygiene program.....check around for affordable options.
9)the sores you mention sound like canker sores - they may have been caused by b12, folate or iron deficiency.....all of which are being corrected on your current diet.
10)consider a sonicare toothbrush or higher end oral-B electronic toothbrush
Hope you get some relief soon.