Suggest Treatment For Headache And Metallic Taste In Mouth

Have had headaches,all over my head, not just one area for 2 yrs now.Had CT, MRI, lots of blood tests,chiropractic care, eye tests etc...in last about 10 months had metallic taste almost constantly in mouth and when tongue touches teeth(weird I know).Im really sick of this and finding increasingly hard to cope.Sometimes headaches worse but generally 'moderate'.Also had episode of TIA about 7months ago but no cause found.Have tried amitrytilene and nortriptylene(up to 80mg) but with no relief.Currently not taking any medication.Any ideas?GP's seem to be scratching their heads...Im not sure what to try next.