My Daughter Has Been Shivering Since 10pm Last Night. It

My daughter has been shivering since 10pm last night. It is making her body ache. She is 19, has no fever, is not using medications and has smoked weed, but not since Thursday. She also said her stomach has been hurting, and some of the time she has been a bit breathless. Any idea what this could be? She is at college and the health center there told she has flu. Since she is not coughing and has no fever so that doesn't sound like flu to me. She is not congested. She does have hypothyroidism and insulin resistance but has not been taking her meds for this for some time.