Hai,
Body temperature of every individual will differ Depending on the place,race,atmosphere.
As per the modern science human body temperature is around 98 to 99 degree Fahrenheit. If your wife is active and healthy no need for any treatment even her body temperature remain between 99 to 100 degree Fahrenheit.
Weakness occur in many condition. physiological weakness happens at day end,poor food intake,
sleeplessness etc.
As your all investigation remain normal No need to worry about pathological cause.
As per ayurvedic concept, i will advise you to take oil bath twice in a week.
(use sesame oil)
make the day free. get up at 6 clock and apply oil in ur head and apply it on the whole body (specifically in arm pit,anus,
umbilicus,genitalia)
leave it for 30 minutes and take bath in warm water. with herbal powder.take steamed food and leafy vegetables. no fried.,spicy food.
dont sleep in day. go to bed earlier around 8 clock at night.
the whole day dont travel.
This mechanism will regulate Ur internal organ and the system to get refresh physically and mentally.
As a whole your body temperature will get regulate.
Hope i answered your query.
Thank you