Stress can be the cause but Headache and low grade temperature for long might create pathology. Just go for investigation like blood test etc. To diagnose what's the problem. Allergies are very well deal with Homoeopathy.
Next Steps
Go for routine blood check up for CBC, random blood
sugar and urine routine. this will help to know gravity of condition.
Health Tips
Get consultation online for allergies and other conditions after the tests. Thanks.