My mom has metastatic tnbc and stopped doing chemo two months ago. she keeps going from being very hot to being very cold. what could be the cause?

Counts, infection: It could be due to blood counts being low, from the prior chemotherapy as well as from the cancer. This can also contribute to the possibility of infection. If she has a port that could be infected, infection in the blood, and other potential places as well. Contact her medical oncologist ASAP as they may want her to go the emergency room for labs and potentially IV antibiotics.