Thanks for asking your query on Healthcaremagic.
Fever usually signifies an infection, most commonly is due to viruses.
I would advise you:
1. To keep record of temperature
2. Try anti-fever medicines like Paracetamol
3. If fever is not subsiding with these medicines or any other symptoms appear, considering his age - you should get him checked over by your family doctor
4. Ensure he is taking orally enough
5. Regarding
constipation - I would like to know if that has been long-standing? If it has been ongoing for couple of weeks, have you tried any medicines for that? If his tummy is hurting due to constipation, he would need to take more liquids, high-fibre diet (like fruits/green leafy vegetables) and may be laxatives.
I hope he recovers soon
Regards
Dr Tejas Shah
Pediatrician