I suspect this reflects an infection somewhere.
Take your temperature for a few days.

Spells of low blood sugar may do this also.
I get the shivers when I have a severe GI spasm.

Diverticulosis,
Prostatitis,
Sinus infections
Gall bladder infections
Hepatitis
Chronic appendicitis
bacterial endocarditis
and many others....

All can simmer in a low grade way.

Do you get the shivers around 4pm or
4am? Chronic issues flare when cortisol
Is low.

Cold intolerance comes with low thyroid but
I never had shivers with mine .. Just a
Deep bone cold pain.

I'd discuss this with your doctor. Shivers are a serious symptom of something wrong in your body.
After using antibiotics it is possible to develop what is called a nosocomial infection. This occurs when the antibiotic kills off many germs (broad spectrum types are most common) and the remaining few pathogens not susceptible grow in abundance and create a new infectious problem.