sudden raises in body temp/ like hot flushes..

Hi all I wanted to ask if anyone gets this? like your temp has gone up high very suddenly …doesn’t last long but can happen day or night…and worse on exercise…ie it’s more intense and prolonged…than any other time… I get clammy and sweaty on my face and neck…and sometimes upper chest…the it just goes…very strange…pretty sure it’s not the change…had blood tests not long ago re the change and wasn’t near it at all… this has been happenning since I was in hospital and at firsts thought it was due to the paracetamol running out …and maybe as uti as I had allot of those when in there… em x