Chronic tension headaches most probably has to do with inflammation coming from inflammatory foods in your diet. I would suggest curcumin from tumeric but make sure to be getting at least 1000mg of curcumin, then a good quality omega 3 supplement of at least 1-2grams of dha/epa (sardines are the best natural source of dha/epa and they're cheap). Both of these should really reduce your body's inflammation which is also causing inflammation in your brain and therefore your chronic tension headache. Im not a pro but these have helped me a lot.