I Am A Female, 37 Years Old, With 4 Children.

I am a female, 37 years old, with 4 children.
I have had a terrible persistant headache for two days,
{No relief with over the counter pain medication.]
along with nausea, middle to lower backache, fatigue and chills, some loose stool.
The aches and pain has kept me from sleeping much.

I started a keto low carb diet, about 8 weeks ago. And have lost about 17 lbs.
I was feeling great, no sickness, until 2 days ago.
Do you know what could causing this?

Thank you, in advance.