I have a white coating on my tongue, and wiping it off makes it bleed and hurt.

A white coating that bleeds and hurts when wiped may not be ordinary tongue coating but oral candidiasis, a fungal infection, so it needs examination. Candidiasis is more likely 1) if you sleep with dentures in or do not clean them enough, 2) if your immunity is lowered by a condition such as diabetes, or 3) if you use antibiotics or a steroid inhaler long term. Treatment is an antifungal - a rinse, ointment, or oral medication - together with correcting the cause so it recurs less. However, a white lesion that has not healed in 2 weeks needs other mucosal conditions ruled out, so please come in.