Is it the heat???

Hi everyone, just a quick question. Since last Friday I have been having dizzy spells (an old symptom I last had 3 years ago), I thought it was triggered by becoming overheated at work and a poor nights sleep last Thursday. However, it’s getting worsehaveven I have an appointment at relapse clinic tomorrow. Hoping it’s not a relapse. Just wanted to know if anyone else has experienced anything similar? And any advice on coping with it?