White crust and bitter taste in my tongue?

Medical condition: Usually when there is a change in tongue tasting and abnormal tongue morphology with no reason, there is a need tin seeking for medical help. Sometimes it is because the influence of your food/medication you currenly have or sometimes is from unbalanced hormone or degeneration of sensry nerve, salivary glands or dry mouth condition, and...Etc. Please consult with your physician for answer.