Brief Answer:
Oral ulcers are due to stress & tissue injury.

Detailed Answer:
Hi

Thanks for writing in.

There are multiple causes of oral ulcers like:-
- stress
- trauma
- vitamin deficiency
- sharp tooth or faulty filling
- systemic diseases like gastro intestinal diseases or herpes etc.
- hormonal changes
- impaired immune system

As such there is no relation between body heat & oral ulcers.
You need to rule out the exact cause & get it treated accordingly.
You may apply anaesthetic gel over it for temporary relief & do tetracycline mouthwash everyday.
Also take multivitamin capsules daily.
If ulcer persists more than 3 weeks consult dentist.
For other skin rashes problem consult your physician.

Hope I answered your query

Wishing you good health

Regards
Dr. Neha Sumra

---