I don't think the mastic gum is causing this... More likely an imbalance of minerals...maybe too much lithium, not sure...
Need to find a B complex or multivitamin if not getting any B vitamins elsewhere...
Thorne Research makes an excellent multivitamin for those with methylation issues...uses active forms of folate, B12, B6 & I think B2... Basic Nutrients 2/Day -
www.thorne.com/Products/Multiples/All_Multis/prd~VM2.jsp May also need to add mercury binders... kick-starting methylation can cause metals dumping, and without binders to get rid of them, they'll just get redistributed elsewhere...