Thanks for writing to the forum!
Bitter taste in mouth is a common side effect of many medications. It could be due to infection of gums or cavities in teeth. It could also be an abnormal perception of bitter taste called dysgeusia. GERD and heart burn too cause metallic taste in mouth. Post nasal drip as in sinusitis, salivary glands infection,pharyngitis or strep infection too are common causes. Certain dentures and artificial tooth or filling of dental cavities too give a metallic taste. Sjogren’s syndrome and copper or lead toxicity are other possibilities.
OK here are a few tips for you. Try them. They should help. Having citrus juices, lemonade and foods marinated in vinegar. They help in washing away the metallic taste by producing more saliva. Brush your teeth and your tongue with a tongue cleaner at least twice in a day and surely at bedtime. It will help in lessening the metallic taste. Vit C tablets, over the counter oral mouthwashes will help fight the taste.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!