Hi Welcome to HCM
As your age is 65 yrs ,
nausea persistantly for 6 days can be caused by BP/ low BP
You must go to your physician to get your self checked thoroughly .
Nausea can be due to many cases It can be due to lack of enrgy , due to sleepless ness , due to less intake of food or consumtion of idigestable food .
or imbalace of air , felm and heat , 3 factors on which our digestive system works according to Ayurveda
Due to
constipation also you feel nausea Or toothache may be reason ?
So , introspect and ascertain the cause , work towards that , half of the trouble is gone .
Try to concentrate on your food . It should contain fiber ,
vitamins , minerals , protien- lots of veges , fruit milk , buttermilk , ginger , garlic ,all antioxidant in all meals .
A lemon in a glass of water in the morning . and befor meals.
Regular Proper exercise , walk ,
yoga / panayam for 40 mins
The above regimen will help lead healthy disease free life .
But Visit your dr urgently . All the best
Don't hesitate to get back if have further query