I wouldn’t use a Proxa brush if your gingiva are inflamed – it will likely irritate the interdental papilla. Flossing daily and brushing twice daily with a fluoride containing toothpaste are crucial. Proper brushing technique is also really important – you have to make sure to massage your gums – best way is to hold brush horizontally and at a 45 degree tilt at your gum line, such that the brush is contacting both your teeth and your gums.
And minimize snacks to meal times – there is more saliva then, which buffers the acidic effect of cavity causing bacteria.