Any Runners with Multiple Sclerosis?

I USED TO run. "USED TO" as in past tense. Almost ten years and 70 lbs past tense. I stopped running when I got pregnant with my fifth baby and had morning sickness all the time. Now I would like to do something like the Couch to 5K plan to get back to it, but my doctor said I am not supposed to get hot enough to raise my body temperature. Oh, and to add to the challenge, I live where the temperature is in the high 80F and 90% humidity year round. Any ideas? What do you do? Do you take more breaks, stop if you are feeling overheated, or just do it anyway? Should I just do a different exercise? Swimming is not an option right now. Thanks!