The roof of the inside of my mouth hurts bad. whys that?

Mouth pain: If no signs of infection , ulcer, fungal infection, consider if eating hard potato chips or doritos could have scrapped the roof of your mouth.

A few possibilities:: Pain is a non-specific symptom that can reflect a wide variety of things-- anything from physical injury, to an infected tooth, to a viral mucous membrane infection. Rather than guess, your best next step would be to arrange for a formal diagnostic session with your dentist so that the cause can be determined; after that, it will be possible to devise an appropriate remedial course of treatment.