I think it is feasable that it is caused by the reduction in vitamin c, one of the causes of swollen gums is low vitamin c. Even though your levels of vitamin c levels are high they are now much lower then what your body was accustomed to.So your gums might now believe they are deficient in vitamin c. http://www.oramd.com/swollengums/42-swollengumsmaynotberesultofnotbrushing.htm/