Without seeing physically its difficult to say. is your roughness associated with pain or burning sensation.if not..its mostly nothing.

Does it burn when you consume any food? Avoid using any gels/ mouthwashes without consulting a doctor first. And don't overdo their usage- sometimes they can worsen a problem when used incorrectly or for a prolonged duration. Do not worry. It's common to have texture on our tongue. Attach a picture for better understanding. Avoid looking at the mirror and stressing yourself. Divert your attention to other mindful activities. Avoid drinking colas, oily and spicy food.