After eaten anything sour, sweet, hot, or spicy I have red/white sores that develop in my mouth. Sometimes even without eating anything. Know why?

Hypersensitive. It appears that the oral mucosa has become hyper-sensitized to the ingredients in those types of food. I would suggest avoiding those types of food items for a week or so, to see if that helps the problem. If no, you may need to be seen by your physician to help resolve this.
Apthous ulcers? This could be recurrent apthous stomatitis which is an autoimmune condition that is generally triggered by certain foods or stress. Most cases are minor and heal on their own within 7-10 days. Severe cases can be medicated with oral topical steroid treatment. This is something that needs to be looked at by your dentist during a flare up to confirm.